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Published byShannon Welch Modified over 9 years ago
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A covalent bond is formed when two or more nuclei share electrons in order to achieve a stable electron configuration (noble gas). Covalent bonds often occur between two non- metals of the same element. (Diatomics) H,O,F,Br,I,N,Cl Atoms of different elements can also combine to form a covalent bond. Example: water, carbon dioxide
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There are different types of covalent bonds. They are: Non-polar Covalent Polar Covalent Multiple Covalent Double bonds Triple bonds
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A nonpolar covalent bond exists when there is an equal sharing of electrons between two nuclei. Nonpolar covalent bonds are formed between atoms having equal or close electronegativity values. The diatomics always make nonpolar covalent bonds because they are non-metals and their electronegativity values cancel. If the electronegativity different is between 0 and 0.4 the compound is considered nonpolar covalent.
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Atoms involved in a polar covalent bond have an unequal sharing of electrons. This can be determined based on their differences in electronegativity. The element with the higher electronegativity value attracts the shared electrons more strongly. This causes a portion of the molecule to acquire a partially negative charge. The other end of the polar molecule acquires a partially positive charge.
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H-Cl and H-I are two common polar compounds. Hydrogen obtains a partially positive charge and the halogens obtain a more negative charge. This happens because the halogens (group 17) have a higher electronegativity value than hydrogen.
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Water is a polar covalent compound. In a water molecule, the oxygen atom takes on the negative charge and the hydrogens take on the positive charge.
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Atoms in covalent bond may share more than one pair of electrons. This additional sharing of electrons results in the formation of a multiple covalent bond. Double bond- the sharing of two pairs of valence electrons. Triple bond- the sharing of three pairs of valence electrons.
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Every Hydrogen atom has one line connecting it to other atoms or itself. (single bond) Every Oxygen atom has two lines connecting it to other atoms or itself. (double bond) Every Nitrogen atom has three lines connecting it to other atoms or itself. (triple bond) Every Carbon atom has four lines connecting it to other atoms. (not itself because Carbon is not diatomic) – (single bonds)
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HH(single) O O(double) NN(triple) ClCl(single)
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A molecule is the smallest discrete particle of an element or compound formed by a covalent bond. Each atom in a molecule obtains an electron configuration of a noble gas. Molecular substance can either be solid, liquid, or a gas. The state of matter depends on the strength of the forces of attraction. Molecules tend to be soft, poor conductors of heat and electricity, and they have low melting and boiling points.
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A large majority of all chemical compounds on Earth are covalent (either polar or non-polar). A vast majority of covalent compounds are organic, meaning they contain carbon and hydrogen. Plastics, foods, living things, oil, etc. are all organic compounds. There are thousand of these compounds and we use them everyday.
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If a molecule contains polar bonds does not mean that the compound itself is polar. For example, the Hydrogen – Carbon bond is polar but the compound CH4 is a non-polar compound. To understand this, one must look at the molecules shape. Asymmetrical molecules are polar Symmetrical molecules are non-polar because the pull of the various polar bonds offset each other.
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Polyatomic ions are two or more different atoms bonded together that act as one unit. Polyatomic ions must also contain an ionic bond to be considered stable. The bonds that hold the polyatomic ion together are covalent. A polyatomic ion plus a metal will contain both ionic and covalent bonds.
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Ionic, metallic, and covalent bonds all have different properties. This table explains the main difference between all three BondMelting/BoilingHardnessConductivity SLAq. MetallicHighHardYes CovalentLowSoftNo IonicHighHardNoYes
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Molecules have attractive forces acting on them in the solid, liquid and gaseous state. These forces are: Ionic forces Dipole forces Hydrogen bonding Induced dipole
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