Use common denominator (3) 21/3 + 1/3. Now you can add. Reciprocal = flip the fraction. 3/22-Definition: two reciprocal numbers, when multiplied together, give a product of 1. What is one contrast between Salva and Nya in these two scenes? Nya is in Sudan, and Salva is in New York. They both feel great joy. Both scenes take place in the same year. Nyaâs family is together and Salvaâs family has been separated. What theme about survival does Park convey by juxtaposing these two scenes?
Ecclesiastes 3:7
A time to tear apart and a time to sew together; A time to be silent and a time to speak.
Jump to:
Nave's Topical Bible - Speaking; Tongue; Thompson Chain Reference - Arts and Crafts; Keep Silence; Sewing; Silence; Silence-Speech; The Topic Concordance - Time; War/weapons;
Baker Evangelical Dictionary of Biblical Theology - Time; Fausset Bible Dictionary - Garden; Holman Bible Dictionary - Ecclesiastes, Book of; Israel, History of; Poetry; Time, Meaning of; Hastings' Dictionary of the Bible - Ecclesiastes; Wilson's Dictionary of Bible Types - Ass; Rend;
S.O.S MATHematics home page. Do you need more help? Please post your question on our S.O.S. Mathematics CyberBoard. 3.3: Molecule Orbital (MO) Theory Expand/collapse global location 3.3.7: When Different Atoms Bond Together (Heteronuclear diatomic molecules).
International Standard Bible Encyclopedia - Providence; Silence; The Jewish Encyclopedia - Temurah, Midrash;
Every Day Light - Devotion for September 24;
Range SpecificChapter Specific
A time to rend, - sew, - keep silence, - speak - -
'Intestine broils
And factions rend a state: at length the breach
Is heal'd, and rest ensues. Wisdom restrains
The tongue, when words are vain: but now,
'Tis time to speak, and silence would be criminal.'
Bibliographical Information
Clarke, Adam. 'Commentary on Ecclesiastes 3:7'. 'The Adam Clarke Commentary'. https://www.studylight.org/commentaries/acc/ecclesiastes-3.html. 1832.
Rend - i. e., Tear garments in sign of mourning or anger. See 2 Samuel 1:2, 2 Samuel 1:11 ff.
Bibliographical Information
Barnes, Albert. 'Commentary on Ecclesiastes 3:7'. 'Barnes' Notes on the Whole Bible'. https://www.studylight.org/commentaries/bnb/ecclesiastes-3.html. 1870.
Ecclesiastes 3:7
A time to keep silence.
Silence
There is a proverb which says, Speech is silvern, silence is golden. Like all proverbs, this admits of qualification. There is a silence that means cowardice, sulkiness, and stupidity; and there is a speech that is more precious than any gold, triumphant over error and wrong, quickening and beneficent as the sunbeam. Notice two or three kinds of silences.
I. There is the silence of emotional fulness. It is a physiological fact that great emotions choke the utterance.
1. Great painful emotions do this (Matthew 22:12). Will not all the wicked who stand at the bar of their Maker at the last day be struck with this silence? Emotions of surprise, remorse, despair, will rush with such tumultuousness upon them as to paralyze all articulating power.
2. Great joyous emotions do this. When the father embraced his prodigal son, his heart was so full of joyous feelings that he could not speak. It has been said that superficial emotions chatter, deep emotions are mute: there are joys that are unutterable.
II. There is the silence of Pious resignation. It is said that Aaron held his peace, and the psalmist said, âI was dumb and opened not my mouth because Thou didst it.â This indeed is a golden silence: it implies unbounded confidence in the character and procedure of our Heavenly Father. It is a loving, loyal acquiescence in the will of Him who is all-loving, all-wise, and all-good. This silence reveals--
1. The highest reason. Is there a sublimer philosophy than this?
2. The highest faith. Faith in the immutable realities of love and right.
III. There is the silence of holy self-respect. This was the silence which Christ displayed before His judges. He seemed to feel that to speak to such virulently prejudiced creatures would be a degradation. The man who can stand and listen to the language of stolid ignorance, venomous bigotry, and personal insult addressed to him in an offensive spirit, and offer no reply, exerts a far greater power upon the minds of his assailants than he could by words, however forceful. His silence reflects a moral majesty, before which the heart of his assailants will scarcely fail to cower. (Homilist.)
A time of war, and a time of peace.--
The Christian view of war
There are those, among the most conscientious of men, who maintain that war is never permissible, that it has always the nature of sin. Among Englishmen the Quakers have clung to the doctrine of non-resistance as one of their most distinctive tenets; among modern thinkers Count Tolstoi has restated it with considerable force. They have based their argument not so much upon the general tenor of Christâs teaching as upon misinterpretations of isolated texts--e.g. âResist not evil,â âAll they that take the sword shall perish with the sword.â It is to their honour that they have been consistent in their interpretation of such passages, often to their own loss, and have applied them both to individual and to national conduct. Yet it is strange that they have not seen how far their argument carries them, and how by exaggerating one counsel of the Gospel they have made other of its precepts of none effect. Toleration of personal injury, to the point of self-effacement, is indeed enjoined upon Christians, but only so far as it does not conflict with other laws of justice and the like. Non-resistance, tolerance of evil and injustice from an individual, may often be most dangerous to society, as an encouragement to crime; and to let an offender go free may be to do him no kindness, but the cruelest of injuries. As with individuals, so with nations. National injustice, greed, insolence, is to be resisted as a danger to humanity. And those who make their appeal to isolated passages of Holy Scripture may be answered by other considerations. To take one only, it may justly be argued that if it were unlawful to wage war, as they assert, it would be unlawful for the Christian to bear arms, and that the soldierâs calling would be reprobated in the New Testament. But the exact opposite is the case. The soldierâs calling is treated as of equal honour with others, a vocation in which God may be well and truly served. The Christian life is itself compared to a warfare, in which the soldier of Christ is exhorted to fidelity by the example of the Roman soldier. The soldiers who inquire their duty of St. John the Baptist are not told to forsake their calling, but to exercise it with justice and mercy. And from Cornelius, the devout man whose prayers and alms were accepted of God, to St. Martin and General Gordon, a long line of soldier-saints bears eloquent witness to the fact that the grace of God may be looked for, and will bear fruit, in that vocation as in others. We may even go further, and say that war and the military vocation undoubtedly develop in nations and in individuals certain of the simpler virtues. It is often through war, as Mr. Ruskin has told us, that âtruth of word and strength of thoughtâ are learnt by nations. âPeace and the vices of civil life only flourish together. We talk of peace and learning, and of peace and plenty, and of peace and civilization; but I found that these were not the words which the muse of history coupled together: and that on her lips the words were--peace, and sensuality--peace, and selfishness--peace, and death.â No less marked are its bracing effects upon the individual. âOn the whole, the habit of living lightly hearted in daily presence of death, always has had, and always must have, power both in the making and testing of honest men.â Many a man by losing himself has found himself, and through the stern discipline of the soldierâs life has gained the self-control which otherwise he would have lost. In war men have the opportunity of rising to higher levels of virtue than they would have thought possible of attainment. From Sir Philip Sidney, dying in agony on the field of Zutphen, and refusing the water which another seemed to need more, to the trooper in Matabeleland who gave his horse--and with it his life--for a wounded comrade, there are countless instances of noble unselfishness developed under the stress of sudden decision, sometimes in the most unexpected characters. Nor, if we be wise, shall we complain that the cost is too great. We cannot know that those who have died nobly would have lived nobly. And so we cannot refuse the conclusion that warfare is not necessarily wrong in itself; that it is lawful âfor Christian men, at the command of the magistrate, to wear weapons and to serve in the warsâ: that war is even in some cases a gain in that it tends to the development of national and individual virtues. But of course when this is conceded we are still very far from admitting that it is ever to be undertaken âwith a light heart,â as the French declared war upon Prussia. The amount of direct and indirect suffering which it causes, immeasurable as that is, is not the greatest of the evils which war brings inevitably in its train. The racial hatreds which it engenders often linger on for scores of years, smouldering fires which a chance gust of passion may easily fan again into flame. Nor can we regard it in any sense as an appeal to the Divine justice, as our forefathers regarded it. War is infinitely the most wasteful, crudest, and least just way of settling international quarrels. And above all, for all its indirect gains, it is to be avoided by Christian nations to the very limits of forbearance, because it hinders the progress of mankind towards the ideals of peace and brotherhood which the Incarnation revealed. War, however just, is an acknowledgment that Christian methods and Christian love have so far failed to be effective. We inquire, lastly, on what conditions warfare may be pronounced justifiable. St. Thomas Aquinas defines the conditions as three in number--the command of the prince, a just cause, and a good intention. The Christian will not hesitate to justify wars morally safeguarded by regard to these conditions. And yet for all that may be said in justification of warfare, war will ever remain a thing grievous to the Christian, ranking with the famine and the pestilence as scourges of God. Upon all Christians there is laid the supreme duty of striving continually for peace, and in these days of democracy no one is without his share of responsibility for national acts. Christians will not shrink from just wars; at the same time they will denounce wars of aggression for material gain. They will endeavour to emphasize the overwhelming responsibility of those in whose power it is t,o declare war, and of those who may influence their decision. They will lose no opportunity of dissociating themselves from those who wantonly disturb the peace of nations, by fostering race-hatreds, magnifying disagreements, offering petty insults, whether in the columns of an intemperate Press, or in any other way. They will promote the principles of arbitration; for though the arbitrators between nations are not backed by force, and cannot compel submission to their decisions, and though long centuries may pass before arbitration can supersede war, yet there is among nations a growing desire to settle differences by that method--an increasing disposition to submit to arbitration, because the justice of the principle is acknowledged. Above all, they will not be ashamed to assert their belief in the efficacy of prayer to the Lord mighty in battle, who is also the Prince of peace, that He would direct aright the counsels of the nations, and would give peace in our time. Who can doubt that wars, in Christendom at least, would soon become rare if all Christians were continually to pray from their inmost heart that God would give to all nations unity, peace, and concord? (E. H. Day, M. A.)
Copyright Statement
These files are public domain. Text Courtesy of BibleSupport.com. Used by Permission.
Bibliographical Information
Exell, Joseph S. 'Commentary on 'Ecclesiastes 3:7'. The Biblical Illustrator. https://www.studylight.org/commentaries/tbi/ecclesiastes-3.html. 1905-1909. New York.
A time to rend, and a time to sew,.. To rend garments, in case of blasphemy, and in times of mourning and fasting, and then to sew them up when they are over; see Isaiah 37:1; This the Jews apply to the rending of the ten tribes from Rehoboam, signified by the rending of Jeroboam's garment, 1 Kings 11:30; the sewing up or uniting of which is foretold, Ezekiel 37:22. Some interpret it of the rending of the Jewish church state, signified by the rending of the vail, at the death of Christ; and of the constituting the Gospel church state among the Gentiles;
a time to keep silence, and a time to speakF11ÏÏη μεν ÏολεÏν μÏ
θÏν, ÏÏη δε και Ï
ÏνοÏ
, Homer. Odyss. 11. v. 378. ; when it is an evil time, a time of calamity in a nation, it is not a time to be loquacious and talkative, especially in a vain and ludicrous way, Amos 5:13; or when a particular friend or relation is in distress, as in the case of Job and his friends, Job 2:13; or when in the presence of wicked men, who make a jest of everything serious and religious, Psalm 39:1; and so when under afflictive dispensations of Providence, it is a time to be still and dumb, and not open the mouth in a murmuring and complaining way, Leviticus 10:3. And, on the other hand, there is a time to speak, either publicly, of the truths of the Gospel, in the ministry of it, and in vindication of them; or privately, of Christian experience: there is a time when an open profession should be made of Christ, his word and ordinances, and when believers should speak to God in prayer and praise; which, should they not, the stones in the wall would cry out.
Copyright Statement
The New John Gill's Exposition of the Entire Bible Modernised and adapted for the computer by Larry Pierce of Online Bible. All Rights Reserved, Larry Pierce, Winterbourne, Ontario. A printed copy of this work can be ordered from: The Baptist Standard Bearer, 1 Iron Oaks Dr, Paris, AR, 72855
Bibliographical Information
Gill, John. 'Commentary on Ecclesiastes 3:7'. 'The New John Gill Exposition of the Entire Bible'. https://www.studylight.org/commentaries/geb/ecclesiastes-3.html. 1999.
rend â garments, in mourning (Joel 2:13); figuratively, nations, as Israel from Judah, already foretold, in Solomonâs time (1 Kings 11:30, 1 Kings 11:31), to be âsewedâ together hereafter (Ezekiel 37:15, Ezekiel 37:22).
silence â (Amos 5:13), in a national calamity, or that of a friend (Job 2:13); also not to murmur under Godâs visitation (Leviticus 10:3; Psalm 39:1, Psalm 39:2, Psalm 39:9).
Copyright Statement
These files are a derivative of an electronic edition prepared from text scanned by Woodside Bible Fellowship. This expanded edition of the Jameison-Faussett-Brown Commentary is in the public domain and may be freely used and distributed.
Bibliographical Information
Jamieson, Robert, D.D.; Fausset, A. R.; Brown, David. 'Commentary on Ecclesiastes 3:7'. 'Commentary Critical and Explanatory on the Whole Bible'. https://www.studylight.org/commentaries/jfb/ecclesiastes-3.html. 1871-8.
7 a . âTo rend has its time, and to sew has its time.â When evil tidings come, when the tidings of death come, then is the time for rending the garments (2 Samuel 13:31), whether as a spontaneous outbreak of sorrow, or merely as a traditionary custom. - The tempest of the affections, however, passes by, and that which was torn is again sewed together.
Perhaps it is the recollection of great calamities which leads to the following contrasts: -
7 b . âTo keep silence has its time, and to speak has its time.â Severe strokes of adversity turn the mind in quietness back upon itself; and the demeanour most befitting such adversity is silent resignation (cf. 2 Kings 2:3, 2 Kings 2:5). Qr factory professional qr code creator 2 9 5. This mediation of the thought is so much the more probable, as in all these contrasts it is not so much the spontaneity of man that comes into view, as the pre-determination and providence of God.
The following contrasts proceed on the view that God has placed us in relations in which it is permitted to us to love, or in which our hatred is stirred up: -
Copyright Statement
The Keil & Delitzsch Old Testament Commentary is a derivative of a public domain electronic edition.
Bibliographical Information
Keil, Carl Friedrich & Delitzsch, Franz. 'Commentary on Ecclesiastes 3:7'. https://www.studylight.org/commentaries/kdo/ecclesiastes-3.html. 1854-1889.
A time to rend, and a time to sew; a time to keep silence, and a time to speak;
To rent â When men rend their garments, as they did in great and sudden griefs.
Copyright Statement
These files are public domain and are a derivative of an electronic edition that is available on the Christian Classics Ethereal Library Website.
Bibliographical Information
Wesley, John. 'Commentary on Ecclesiastes 3:7'. 'John Wesley's Explanatory Notes on the Whole Bible'. https://www.studylight.org/commentaries/wen/ecclesiastes-3.html. 1765.
Ecclesiastes 3:7 A time to rend, and a time to sew; a time to keep silence, and a time to speak;
Ver. 7. A time to rend, and a time to sew.] As in making a new or translating an old garment. Turks wonder at the English for pinking or cutting their clothes, and making holes in whole cloth, which time of itself would tear too soon. (a) It was a custom among the Jews to rend their clothes in the case of sad occurrences. The prophet Ahijah rent Jeroboamâs new garment in twelve pieces, to show that God would rend the kingdom out of the hand of Solomon. [1 Kings 11:31] Schismatics rend the Church, heretics the Scriptures. God will stitch up all in his own time, and heal the breaches thereof. [Psalms 60:2]
A time to keep silence, and a time to speak.] It is a singular skill to 'time a word,' [Isaiah 50:4] to set it upon its wheels, [Proverbs 25:11] as Abigail did for her family, [1 Samuel 25:23-31] as Esther did against Haman. And it is a happy thing when a man can pray, as one once did, Det Deus ut sermo meus adeo commodus sit, quam sit accommodus, God grant my speech may be as profitable as it is seasonable. He that would be able to speak when and as he ought, must first learn silence, as the Pythagoreans did of old, (b) as the Turks do at this day, Perpetuum silentium tenent ut muti, they are not suffered to speak. Discamus prius non loqui, saith Jerome upon this text. Let us first learn not to speak, that afterwards we may open our mouths to speak wisely. Silence is fitly set here before speaking, and first takes its time and turn. It is a good rule that one gives, either keep silence, or speak that which is better than silence. (c)
Copyright Statement
These files are public domain. Text Courtesy of BibleSupport.com. Used by Permission.
Bibliographical Information
Trapp, John. 'Commentary on Ecclesiastes 3:7'. John Trapp Complete Commentary. https://www.studylight.org/commentaries/jtc/ecclesiastes-3.html. 1865-1868.
A time to rend; when men shall rend their garments, as they did in great and sudden griefs, as Genesis 37:29Joel 2:13.
A time to keep silence; wherein men will or shall be silent, either through grief, as Job 2:12,13 Dreadout 1 0 â third person supernatural horror game. , or by sickness or weakness, or because God denies a man ability to utter his mind.
Copyright Statement
These files are public domain. Text Courtesy of BibleSupport.com. Used by Permission.
Bibliographical Information
Poole, Matthew, 'Commentary on Ecclesiastes 3:7'. Matthew Poole's English Annotations on the Holy Bible. https://www.studylight.org/commentaries/mpc/ecclesiastes-3.html. 1685.
7.To rendâ to sewâ keep silenceâ speak â The rending of garments and sitting down in silence is token of great sorrow; the repairing of them and the recommencing of conversation is evidence of the relief of sorrow. These are thus properly grouped in one verse.
Copyright Statement
These files are public domain. Text Courtesy of BibleSupport.com. Used by Permission. Together 3 3 7 30
Bibliographical Information
Whedon, Daniel. 'Commentary on Ecclesiastes 3:7'. 'Whedon's Commentary on the Bible'. https://www.studylight.org/commentaries/whe/ecclesiastes-3.html. 1874-1909.
'A time to tear apart, and a time to sew together;'
'This verse may refer to actions associated with mourning (tearing one's clothes and remaining silent; cf. Job )' (Bible Knowledge Comm. p. 984). This principle also applies to friendships and things. There is a time to realize that something can't be fixed, that we are in effect beating a dead horse.
'A time to be silent, and time to speak.'
There are times and situations in which silence is the best policy (James ), especially when you have nothing of value to say (Prov. 17:28), or when you haven't even heard the question yet (Prov. 18:13). There is a time for thoughtful reflection (Prov. 15:28). And then, there is a time to speak out (Prov. 15:23; 25:11; 27:5; Gal. 2:11-14; Eph. 5:11).
Copyright Statement
These files are public domain. Text Courtesy of BibleSupport.com. Used by Permission.
Bibliographical Information
Dunagan, Mark. 'Commentary on Ecclesiastes 3:7'. 'Mark Dunagan Commentaries on the Bible'. https://www.studylight.org/commentaries/dun/ecclesiastes-3.html. 1999-2014.
to rend., 1 Samuel 15:27, 1 Samuel 15:28; 1 Kings 11:11, 1 Kings 11:31; 1 Kings 12:31; 1 Kings 14:8. Joel 2:13. John 19:24.
to sew = to join together, adjust. Spoken of kingdom, as 'rending' is: Ezekiel 37:15, Ezekiel 37:22, and references there. Compare Ezra 4:12, margin.
to keep silence., Leviticus 10:3. Psalms 32:2. Amos 5:13. 1 Timothy 2:11, 1 Timothy 2:12; 1 Peter 2:15. Compare Deu t. Ecclesiastes 3:26. Luke 1:22; Luke 4:41.
to speak., Exodus 7:2. Numbers 22:8. 2 Samuel 7:17. Psalms 2:5; Psalms 145:6, Psalms 145:11, Psalms 145:21. Ezekiel 2:7. Luke 1:19, Luke 1:20. John 16:13.
Copyright Statement
These files are public domain. Text Courtesy of BibleSupport.com. Used by Permission.
Bibliographical Information
Bullinger, Ethelbert William. 'Commentary on Ecclesiastes 3:7'. 'E.W. Bullinger's Companion bible Notes'. https://www.studylight.org/commentaries/bul/ecclesiastes-3.html. 1909-1922.
A time to rend, and a time to sew; a time to keep silence, and a time to speak;
A time to rend - garments, in mourning (Joel 2:13). Figurative, nations, as Israel from Judah, already foretold in Solomon's time (1 Kings 11:30-31), to be 'sewed' together hereafter (Ezekiel 37:15; Ezekiel 37:22). Jacob is the type of the people of God in all ages, who need, like him, to be afflicted temporarily for sin, that self may be mortified, and that so, in God's good time, their rent may be repaired everlastingly (Genesis 37:34; Genesis 45:27-28). The very time when God rent the temple-veil was that wherein he was preparing to destroy 'the veil that is spread over all nations' (Isaiah 25:7).
A time to keep silence (Amos 5:13) - in a national calamity, or that of a friend (Job 2:13); also not to complain under God's visitation (Leviticus 10:3; Psalms 39:1-2; Psalms 39:9).
A time to speak - when God opens the door of utterance to His people (Acts 18:9; 1 Corinthians 16:9; 2 Corinthians 2:12).
Copyright Statement
These files are public domain. Text Courtesy of BibleSupport.com. Used by Permission.
Bibliographical Information A time to rend, and a time to sew; a time to keep silence, and a time to speak;
Jamieson, Robert, D.D.; Fausset, A. R.; Brown, David. 'Commentary on Ecclesiastes 3:7'. 'Commentary Critical and Explanatory on the Whole Bible - Unabridged'. https://www.studylight.org/commentaries/jfu/ecclesiastes-3.html. 1871-8.
Copyright Statement
These files are public domain. Text Courtesy of BibleSupport.com. Used by Permission.
Bibliographical Information
Torrey, R. A. 'Commentary on Ecclesiastes 3:7'. 'The Treasury of Scripture Knowledge'. https://www.studylight.org/commentaries/tsk/ecclesiastes-3.html.
Ecclesiastes 3:7. A time to rend, and a time to sew. There is a time when the people of God must mourn, and again a time when they can rejoice, קרע is used with special reference to the rending of the clothes, which in Israel was a sign of mourning. When it is said in Genesis 37:34, 'and Jacob rent his clothes, and put sackcloth upon his loins, and mourned for his son many days,' we recognize in Jacob a type of the people of God and of the Church in all ages, a prophecy in the form of a fact which is being fulfilled ever afresh. Where there is the like cause, there is the like result. Was it necessary that the ancestor should be visited with severe afflictions on account of his sinfulness, for the same reason must his descendants also suffer, and to preserve their heart from exalting itself God ordains that through much tribulation they shall enter his kingdom, that times of refreshing from His presence shall alternate with times of sorrow, and His unchangeable love disguises itself in many ways and frequently appears under forms fitted to awaken terror. In Joshua 7:6 we read, 'and Joshua rent his clothes, he and the elders of Israel:' and in 2 Samuel 13:31, 'and the king arose and rent his clothes and lay on the earth; and all his servants stood by with their clothes rent.' A time to keep silence and a time to speak. There are times when silence must be observed, as Jacob was compelled to keep silence when he heard how Sichem had defiled Dinah his daughter, until his sons arrived (Genesis 34:5): and then again come times when we may speak and stand up boldly in the presence of the enemies of God's people, as when the Lord spake to Paul in the vision by night, when the Jews of Corinth tried to force him to silenceâ'Be not afraid, but speak, and hold not thy peace,' (Acts 18:9). When the hour appointed by God arrives, the words of Psalms 127:5, 'they shall not be ashamed when they speak with their enemies in the gate,' come fully true. Till then we must cover our faces and keep silence. But it is notwithstanding a blessed silence, for it is attended by the conviction that a time to speak will inevitably come again.
Copyright Statement
These files are public domain. Text Courtesy of BibleSupport.com. Used by Permission.
Bibliographical Information
Hengstenberg, Ernst. 'Commentary on Ecclesiastes 3:7'. Ernst Hengstenberg on John, Revelation, Ecclesiastes, Ezekiel & Psalms. https://www.studylight.org/commentaries/heg/ecclesiastes-3.html.
Two different atoms from the main group often bond together to make diatomic molecules. In most cases, the molecular orbital picture does not change very much from what we have already seen.
From a Lewis point of view, some very simple compounds include the hydrogen halides. For example, HF contains a hydrogen bonded to a fluorine.
A molecular orbital picture of HF could involve an s orbital on hydrogen interacting with an s orbital on fluorine. It may be that the three p orbitals on fluorine stay out of the way, do not interact with the hydrogen, and remain unchanged in the molecule. In that case, we are dealing with a picture of two s orbitals combining, as in dihydrogen.
The only difference is in the starting energy levels of the atomic electrons. The electrons in fluorine are at lower energy than the electron in hydrogen. Thus, the molecular orbital picture is skewed, with one side of the diagram at lower energy than the other.
There is a physical interpretation for this lopsidedness. Notice that the bonding orbital is closer in energy to fluorine than it is to hydrogen. Often, energetic similarity correlates with structural similarity. We think of these bonding electrons as being physically closer to the fluorine as well. In other words, the electrons in this bond are not equally shared, but are held more closely by fluorine.
This idea is consistent with our ideas about bonding between dissimilar atoms. We would think of the H-F bond as a polar, covalent one.
The idea that fluorine's electrons are at lower energy may be confusing. A 1s electron in fluorine is certainly at lower energy than a 2s or 2p electron in fluorine. However, a 1s electron in hydrogen is not necessarily at a lower energy than a 2s or 2p electron in fluorine. All the electrons in fluorine are at lower energy than the electron in hydrogen because fluorine has a much higher nuclear charge, with relatively little shielding from its own 1s electrons. Fluorine has a high Zeff, as evinced by its high electron affinity (high attraction for more electrons) and high ionization potential (large amount of energy needed to strip an electron away).
Exercise (PageIndex{1})
Construct molecular orbital interaction diagrams for the following diatomic molecules. In each case, what is the bond order? Is the compound diamagnetic or paramagnetic?
Attribution
Chris P Schaller, Ph.D., (College of Saint Benedict / Saint John's University)
Diatomic molecules with two non-identical atoms are called heteronuclear diatomic molecules. When atoms are not identical, the molecule forms by combining atomic orbitals of unequal energies. The result is a polar bond in which atomic orbitals contribute unevenly to each molecular orbital.
The application of molecular orbital theory to heteronuclear diatomic molecules is similar to the case of homonuclear diatomics, except that the atomic orbitals from each atom have different energies and contribute unequally to molecular orbitals. Recall that atomic orbitals must have compatible symmetry and similar energy to combine into molecular orbitals. In the case where atomic orbitals of like symmetry have different energies, they combine less favorably than orbitals that are closer to one another in energy. As a general rule, orbitals that have energy differences of greater than 10-14 eV do not combine favorably. In the molecular orbital diagram, the closer a molecular orbital is to an atomic orbital, the more that atomic orbital contributes to the molecular orbital. This last point is helpful for back-of-the napkin estimations of what the molecular orbitals 'look' like.
In this section, you should learn how to generate molecular orbital diagrams of heteronuclear diatomic molecules. To approach such a problem, we must start with a knowledge of the relative energies of electrons in different atomic orbitals. In other words, we need knowledge of the orbital potential energies (or orbital ionization energies).
Orbital Ionization Energies
There are two approaches you can use to 'know' or estimate the atomic orbital energy levels.
1. Use a table of atomic orbital ionization energies, like those found in Table (PageIndex{1}).
2. When you do not have access to a table of values like the one below, use periodic trends in electronegativity and/or ionization energies as your guide to approximate relative values for different atoms.
Sources:
Together 3 3 7 32
Modified or created by Kathryn Haas (khaaslab.com)
Earlier, we talked about the fact that axially symmetric orbitals can mix together to produce new combinations. In HF, we looked at the overlap of the 2s orbital on fluorine with the 1s orbital on hydrogen. However, one of the 2p orbitals can lie along the bond axis and share axial symmetry with the hydrogen 1s orbital.
We will call this fluorine orbital the 2pz orbital. We could just as well label it px or py, but many people refer to the p orbital along the bond axis as the pz. Note that the 2p orbitals that are perpendicular to the bond axis can't interact with the hydrogen 1s orbital. Because the bond axis crosses the p orbital at a node, where the p orbital changes phase, the hydrogen atom can't form either an in-phase or out-of-phase combination with this p orbital. It would actually be in-phase with one part of the orbital and out-of-phase with the other. Instead, these orbitals simply do not interact.
Together 3 3 7 3 64 Bit Download
The third combination is a little more subtle. The other possibility is that the 1s orbital of hydrogen is in-phase with one orbital of fluorine, but out-of-phase with the other. However, that means it could be in-phase with the 2s but out-of-phase with the 2pz, or vice versa. That means there are two more combinations, for a total of four. However, since we are using only three atomic orbitals, we can produce only three molecular orbitals. These two possible combinations must somehow be mathematically reduced to one.
Together 3 3 7 35
Once again, mixing that occurs based on symmetry has some quantitative effects on the energies of the electrons, but in this case the qualitative effect is a subtle change in the ordering of energy levels.
Attribution3.3 Naruto
Chris P Schaller, Ph.D., (College of Saint Benedict / Saint John's University)
Comments are closed.
|
Details
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |