Covalent Compounds

Question 1

Covalent Compounds

Answer 1

Form when 2 Nonmetal atoms share electrons in order to achieve a stable configuration (octet valence).

Question 2

Covalent Bond

Answer 2

• When atoms share ve-
• Most try to achieve an octet (H is stable @ 2ve-)
• represented by a line (single, double, triple, etc)

Question 3

Diatomic

Answer 3

Contains 2 atoms of the same element covalently bonded together.

Eg. H2, F2

Question 4

Electron-dot Formulas of Covalent Compounds

Answer 4

Chemical symbols show side by side surrounded by ve- in Lewis-dot structure with bonds connecting the ve- to achieve the required octet for each atom.

Question 5

of Covalent Bonds

Answer 5

Nonmetals generally form bonds equal to the number of ve- needed to acquire a stable configuration.

Question 6

Exceptions to the Octet Rule

Answer 6

Octet rule is useful but there are exceptions.

Question 7

Lone Pairs

Answer 7

• Paired ve- drawn in the Electron-dot formulas (must be paired if there are enough ve-)
• have much more negative charge than the covalently bonded atoms, thus BEND & CHANGE the shape of the compound.

Question 8

Diatomic Elements

Answer 8

Hydrogen, then the Tetris 7 from G5-7

-H, N, O, F, Cl, Br, I

Question 9

Naming Covalent Compounds

Answer 9

Prefixes are used for both nonmetals because two nonmetals can form 2+ different compounds. The second nonmetal has the suffix -ide.

Prefix-nonmetal + prefix-nonmetal-ide

Eg. NO : Nitrogen (mono)oxide
NO2 : Nitrogen dioxide
N2O: Dinitrogen oxide
N2O4: Dinitrogen tetraoxide

Question 10

Reducing Common Factors in Covalent Compounds

Answer 10

IS NOT DONE!

Eg. N2O4

In Ionic compounds this formula would be reduced, but since these are nonmetals we NEED to know how many ve- are being shared.

Question 11

Prefixes in Latin

Answer 11

1 mono       2 di
3 tri            4 tetra
5 penta      6 hexa
7 hepta      8 octa
9 nona      10 deca

Question 12

Writing Chemical Formulas from Covalent Compound Names

Answer 12

1- write the symbols in the order of the elements in the name
2- write any prefies as subscripts

Question 13

Steps to Writing Electron-dot Formulas

Answer 13

1- determine the arrangement of atoms (elements)
2- determine the ve-
3- attach each bonded atom to the central atom(s) w/pair of ve-
4- place remaining ve- as lone pairs to complete octets (excluding 2 for H atoms)
5- if octets are incomplete, form multiple bonds by converting a lone pair to a bonding pair

Question 14

Electronegativity

Answer 14

The ability of an atom to attract bonding electrons of a covalent bond to itself.
Increases going up and across the PT
-F most electronegative element

Question 15

Molecular Polarity

Answer 15

Unequal sharing of ve- exists when one element in a molecular formula has a higher electronegativity than another element in the formula.

Based on the difference of electronegativity of the elements of a compound, the type of bond can be predicted (nonpolar, polar, ionic)

Question 16

Polar Covalent Bond

Answer 16

Unequal sharing of ve-
Determined by subtracting the difference between elements of a compound
0.5 - 1.7 = polar covalent bond

-denoted using the Greek delta, meaning ‘partial’ (delta + / delta -)

Question 17

Nonpolar Covalent Bond

Answer 17

Equal or almost equal sharing of ve-
Determined by subtracting the difference between elements of a compound.
0.0 - 0.4 = nonpolar covalent bond

Question 18

Ionic Bonds

Answer 18

Has an electronegativity difference of 1.8+
Occurs between metal+nonmetal
Result of a ve- transfer, not sharing

Question 19

Predicting Bond Types

Answer 19

Nonpolar: 0.0 - o.4
Polar: 0.5 - 1.7
Ionic: 1.8+

The greater the electronegativity difference of 2 atoms, the more polar the bond.
The further away 2 atoms are on the PT, the more polar the bond.

Question 20

Dipole Arrow

Answer 20

• |——->

The + of the arrow indicates the more positive atom (lesser electronegativity) while the arrow head points to the more negative atom (greater electronegativity drawing ve- towards it in a covalent compound)