Chemistry: Chapter 8- COVALENT BONDING

Properties of a molecular compound

- lower melting and boiling points than ionic compounds - weaker attraction than ionic bonds - exist as individual molecules

Mono

1

Steps for drawing lewis structures

1. Determine the total number of valence electrons in the compound 2. Determine the needed number for stability 8 or 2 3. Step 1 -step 2 then divide by 2 4. Step 1- step 3

Deca

10

Di

2

Tri

3

Tetra

4

Penta

5

Hexa

6

Hepta

7

Octa

8

Nona

9

Sigma bond

A bond formed when two atomic orbitals combine to form a molecular orbital that is symmetric around the axis connecting the two nuclei

Covalent bond

A chemical bond that results when atoms share valence electrons

What are molecular compounds represented with?

A chemical formula that shows the kinds and numbers of atoms present in a molecule of the compound

Molecular formula

A chemical formula that shows the kinds of numbers of atoms present in a molecule of the compound

Binary molecular compound

A compound that involves two Nonmetals sharing electrons

Molecular compound

A compound that is composed of molecules

Coordinate covalent bond

A covalent bond in which one atom contributes both bonding electrons

Pi bond

A covalent bond in which the bonding are most likely found in sausage- shaped regions above and below the bond axis of the bounded electrons

Non- polar covalent bond

A covalent bond in which the bonding electrons are shared equally between the two atoms

What is another name for a molecular compound?

A covalent compound

VSEPR model

A model used to determine the shape of a molecule

Bonding orbital

A molecular orbital that can be occupied by two electrons of a covalent bond

Diatomic molecule

A molecule that contains two atoms typically of the same element

Molecule

A neutral group of atoms joined together by covalent bonds

What do covalent bonds allows the atoms in the bond to have?

A stable octet

Polyatomic ion

A tightly bound group of atoms that behaves as a unit and has a positive or negative charge

When do covalent bonds form?

Between two Nonmetals

Ionic bond

Bond formed from the attraction of oppositely charged ions

Polar covalent bond

Covalent bond in which the bonded atoms have an unequal attraction for the shared electrons

Which elements are found in nature as diatomic?

Hydrogen, oxygen, nitrogen, and halogens

Resonance structure

One or more of the equally valid leiws structures of a molecule or polyatomic ion

Molecular orbital

Orbitals that apply to the entire molecule

How do you name a binary molecular compound?

Place a prefix on each element's name to show how many of that atom is present Drop the ending of the second element's name and replace with ide

What is the difference for a lewis structure for a polyatomic ion

Place the lewis structure in brackets with the charge outside

How does the lewis structure of a polyatomic ion differ from that of a single ion?

Put the structure in brackets with the charge outside

4 e clouds (2 bonds and 2 unshared)

Shape: bent Bond angle: 105

2e clouds

Shape: linear Bond angle: 180

4e cloud(4 bonded atoms)

Shape: tetrahedral Bond angle: 109.5

3e clouds

Shape: trigonal planar Bond angle: 120

4e cloud (3 bonds & 1 unshared )

Shape: trigonal pyramidal Bond angle: 107

Electronegativity

The ability of an atom to attract electrons to itself when it is chemically bonded

Writing formulas from names

The prefix tells you the number so that number becomes the subscript

Single bonds

The sharing of one pair of electrons between two atoms

T or F: Hydrogen and the halogens are NOT usually bonded to only 1 other atom

The sharing of three pairs of electrons between two atoms

Triple bonds

The sharing of three pairs of electrons between two atoms

T or F: the atom with the lowest electronegativity is usually in the center

True

T or f: if only one of the first element is present, no prefix is used

True

True or false: single bonds are always sigma bonds

True

What does it stand for?

Valence Shell Electron Pair Repulsion

When would you have a resonance structure ?

When multiple bonds are involved

how are molecular compounds different from ionic compounds

a molecular compound is formed by a covalent bond, which involves a sharing of valence electrons. an ionic compound is formed by an ionic bond, which involves either going or losing electrons.

how to draw lewis structures

determine the total number of valence electrons in the compound, determine how many electrons are needed to be stable, determine the number of shared electrons (step 1- step 2) and divide shared by two, subtract shared from valence electrons

lewis structure

diagram that shows the bonding between atoms of a molecule and the lone pairs of electrons that may exist in the molecule

rules for electronegativity

increases as you move upwards in a group (vertical), increase from left to right across a period

how does the VSEPR theory help to predict the shape and bond angle of molecules

scientists use the vesper model to explain the 3d shape of molecules. the theory states that the repulsion between electron pairs causes molecular shapes to adjust so that the valence electron pairs stay as far apart as possible. to determine the shape you count the number of electron clouds surrounding the central atom and predict shape bed on number of clouds

Double bonds

the sharing of two pairs of electrons between two atoms