Department of Chemistry CHEM1010 General Chemistry ***********************************************

Department of Chemistry

CHEM1010 General Chemistry***********************************************

Instructor: Dr. Hong ZhangFoster Hall, Room 221

Tel: 931-6325

Email: [email protected]

CHEM1010/General Chemistry_________________________________________

Chapter 5. (16)-Chemical Bonds• Today’s Outline

..Review of ionic bond

..Covalent bond: Shared electron pair(s), Equal sharing ..Covalent bond: Shared electron pair(s), Unequal sharing..Covalent bond: Multiple bonds

..Names of covalent compounds or molecules..Polyatomic molecules: Water, Ammonia, and Methane..Polyatomic ions

Chapter 5. (L16)-Chemical Bonds

Building Your Chemical Vocabulary

Nitric acid: HNO3

Chock: CaSO4

Carbonic acid: H2CO3 Hydrogen peroxide: H2O2


• Review of ionic bond ..Ionic bond typically occurs to a combination of a metal atom and a non-metal atom to form an ionic compound or molecule:

2Hg(l) + O2(g) = 2HgO(s)Hg: silvery liquid metal

O2: invisible gas

Cl2 + 2Na = 2NaCl

Cl2: greenish gas, typical non-metalNa: typical metal


• Review of ionic bond ..Nature of ionic bond: Electrostatic attraction between cations and anions..Octet outer shell electron configuration

8 electrons in the outmost shell, most stable, the configuration of the noble gases..Octet rule: Metals tend to loose electron(s) to achieve the octet outer shall electron configuration, while non-metals tend to gain electrons to achieve the octet outer shall electron configuration. ..Only valence electron configuration is needed.


• Covalent bond: Shared electron pair(s), equal share, nonpolar ..Non-polar covalent bond occurs to the molecules of the identical atoms:

H· + ·H = H:H = H2 one pair.. .. .. ..

:O: + :O: = :O::O: = O2 two pair .. .. .. ..

:Cl· + ·Cl = :Cl:Cl: = Cl2 one pair .. .. .. ..

..Again, only valence electron configuration is needed.


• Covalent bond: Shared electron pair(s), equal share, nonpolar Hence, by sharing the electrons, each atom thus has an octet electron configuration. ..Covalent bond: The bond formed by a shared pair of electrons..Bonding pair: The shared pair of electrons..Nonbonding pair: The unshared pair of electrons ..Non-polar covalent bond: Both atoms have the same hold on the electrons, so the shared electrons are evenly held by each atom, no preference.


• Covalent bond: Shared electron pair(s), unequal share, polar.. Polar covalent bond occurs to the molecules of atoms of somewhat different kinds (not strongly different), usually non-metals

.. ..H· + ·Cl: = H:Cl: one pair .. ..

H2 + Cl2 = 2HCl..Unequal sharing: Cl atom has more attraction to the electrons than H atom, more electronegative

Cl atom would have a bit more negative charge, while H atom would have a bit more positive charge


• Covalent bond: Multiple bonds

.. ..

single bond, H:H (H2), :Cl:Cl: (Cl2) .. ..

.. ..

double bond, :O:O: (O2) .. .. .. ..

triple bond, N:::N (N2)


• Polyatomic covalent compounds and molecules

..Water, H:O:H 8 – 6 = 2 bonds

.. ..

Ammonia, H:N:H 8 – 5 = 3 bonds ..

H

Methane, H 8 – 4 = 4 bonds ..H:C:H .. H


• Names of covalent compounds and molecules..Common names from everyday life

water, ammonia, methane..Use of prefix

N2O4, dinitrogen tetraoxide

NO2, nitrogen dioxideNO, nitrogen oxide (nitric oxide, nitrogen monoxide)CO, carbon monoxide

CO2, carbon dioxide

SCl2, sulfur dichloride

SF6, sulfur hexafluoride

P2O5, diphosphorous pentoxide

CrO3, chromium trioxide


• Polyatomic ions

hydroxide

.. ..

e- + ·O· + ·H = [:O:H]-

.. ..

lye, a strong base, NaOH = Na+ + OH-

..See table 5.4 on pp.135 of the textbook for more polyatomic ions, both cations and anions


Quiz Time

Covalent bond is formed by (a) sharing one or more pairs of protons between atoms; (b) sharing one or more pairs of neutrons between atoms; (c) sharing one or more pairs of valence electrons between atoms; (d) sharing one or more inner shell electrons between atoms.


Quiz Time

Covalent bonds typically occur to the molecules of (a) typical metal atom(s) and typical non-metal atom(s); (b) identical atoms or atoms of somewhat different atoms; (c) any kinds of atoms; (d) none of above.


Quiz Time

Which covalent bond is polar? Is it (a) the bond between two identical atoms; (b) the bond between a non-metal atom and a metal atom; (c) the bond between two electrons; (d) the bond between two atoms that are somewhat different but not strongly different.

.


Quiz Time

Which covalent bond is non-polar? Is it (a) the bond between two identical atoms; (b) the bond between a non-metal atom and a metal atom; (c) the bond between two electrons; (d) the bond between two atoms that are somewhat different but not strongly different.

.


Quiz Time

Which of the following molecules has covalent bond? Is it

(a) NaCl;

(b) H2O;

(c) CaO;

(d) MgCl2.


Quiz Time

Which of the following molecules has polar covalent bond? Is it

(a) KCl;

(b) H2O;

(c) H2;

(d) Cl2.


Quiz Time

Which of the following molecules has non-polar covalent bond? Is it

(a) AgCl;

(b) H2O;

(c) N2;

(d) HF.


Quiz Time

Which of the following molecules has a single covalent bond? Is it

(a) AgCl;

(b) O2;

(c) N2;

(d) HF.


Quiz Time

Which of the following molecules has a double covalent bond? Is it

(a) AgCl;

(b) O2;

(c) Cl2;

(d) HBr.


Quiz Time

Which of the following is a polyatomic cation? Is it

(a) Br-;

(b) NO3-;

(c) NH4+;

(d) PO43-.


Quiz Time

Which of the following is a polyatomic anion? Is it

(a) Na+;

(b) SO42-;

(c) NH4+;

(d) Cl-.


Quiz Time

Which is the right molecular formula for a covalent compound or molecule, bromine trifluoride? Is it

(a) Br3F;

(b) BrF2; (c) BrF;

(d) BrF3.


Quiz Time

Which is the right molecular formula for a covalent compound or molecule, tetraphosphorous trisulfide ? Is it

(a) S4P3;

(b) S3P4;

(c) P3S4;

(d) P4S3.


Quiz Time

Which is the right name for N2S4? Is it

(a) nitrogen sulfide;

(b) tetranitrogen disulfide;

(c) Dinitrogen tetrasulfide;

(d) non of above.


Quiz Time

Which is the right name for PF5? Is it

(a) phosphorous fluoride;

(b) pentaphosphorous fluoride;

(c) phosphorous pentafluoride;

(d) non of above.


Quiz Time

Which is the right name for NaNO3? Is it

(a) sodium nitrite;

(b) sodium nitrate;

(c) sodium nitrogen;

(d) nitrogen sodium.


Quiz Time

Which is the right name for K2SO4? Is it

(a) potassium sulfate;

(b) potassium sulfide;

(c) potassium sulfur oxygen;

(d) dipotassium sulfur tetraoxygen.


Quiz Time

Which is the right name for K2CO3? Is it

(a) potassium carbon;

(b) potassium carbonate;

(c) potassium bicarbonate;

(d) dipotassium carbon trioxygen.


Quiz Time

Which is the right name for KHCO3? Is it

(a) potassium carbon;

(b) potassium carbonate;

(c) potassium bicarbonate;

(d) dipotassium carbon trioxygen.


Quiz Time

Which is the right name for KNO2? Is it

(a) potassium nitrogen;

(b) potassium nitrite;

(c) potassium nitrate;

(d) dipotassium nitrogen dioxide.


Quiz Time

Which is the right molecular formula for sodium bicarbonate? Is it

(a) NaCO3;

(b) Na2CO3;

(c) NaHCO3;

(d) NaCO.


Quiz Time

Which is the right molecular formula for hydrogen sulfide? Is it

(a) HS;

(b) SH;

(c) H2S;

(d) HS2.


Quiz Time

Which is the right molecular formula for potassium hydroxide? Is it

(a) KH;

(b) KO;

(c) HKO;

(d) KOH.


Quiz Time

Which is the right molecular formula for calcium hydroxide? Is it

(a) CaOH;

(b) CaO;

(c) HCaO;

(d) Ca(OH)2.

Department of Chemistry CHEM1010 General Chemistry ***********************************************

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