CH4: CHEMICAL BONDING

Question 1

What is a compound?

Answer 1

• pure substance
• 2 or more elements
• chemically combined
• in a fixed ratio

Question 2

What are noble gases?

Answer 2

• Elements
• valence shell fully filled with electrons
• attained closed shell electronic configuration.

Question 3

What are the chemical properties of noble gases?

Answer 3

• INERT (chemically unreactive)
• MONOATOMIC (composed of just one atom, lacking any covalent bonds)

Question 4

Why do atoms that are not noble gases combine?

Answer 4

To** gain, lose or share electrons **to fill up their valence shell and attain a **closed shell electronic configuration **.

Question 5

Why are noble gases chemically unreactive/inert?

Answer 5

• have fully filled valence shells of electrons
• closed shell electronic configuration
• are stable

Question 6

Helium has a _______ electronic configuration (Group 18)

Answer 6

duplet

Question 7

Most noble gases have an _______ electronic configuration?

Answer 7

octet

Question 8

3 types of bonds

Answer 8

• covalent
• ionic
• metallic

Question 9

What is an ionic bond?

Answer 9

the mutual ELECTROSTATIC attraction between IONS of OPPOSITE charges

Question 10

atoms GAIN an electron to gain ______ charge to form a/an _______

Answer 10

gain > negative > anion

Question 11

atoms LOSE an electron to gain a ______ charge to form a/an ______

Answer 11

lose > positive > cation

Question 12

define ‘polyatomic’

Answer 12

made from more than 1 atoms

Question 13

define ‘monoatomic’

Answer 13

made from 1 atom

Question 14

define ‘diatomic’

Answer 14

made form 2 atoms

Question 15

anions formed by group 17 elements are called…

Answer 15

Halide ions

Question 16

Why do ionic compounds have no net charge?

Answer 16

They are ELECTRICALLY NEUTRAL > total positive charge from cations = total negative charge from anions

Question 17

Structural properties of ionic compounds:

Answer 17

• ALTERNATING +ive and -ive ions
• closely packed and arranged in an orderly manner
• held together by strong ELECTROSTATIC forces of attraction
• form a GIANT IONIC LATTICE STRUCTURE

Question 18

What is covalent bonding?

Answer 18

The sharing of electrons between atoms to form a closed shell electronic configuration.

Question 19

Define ‘valency’

Answer 19

the number of electron(s) that must be lost, gained or shared in order for the atom to attain a noble gas electronic configuration.

Question 20

Define ‘electronegativity’

Answer 20

The ability of an atom to attract a shared pair of electrons towards itself in a covalent bond.

Question 21

Electronegativity
_______ across a period
_______ down a group
Hence, ______ is the most electronegative atom.

Answer 21

INCREASES across a period
DECREASES down a group
Hence, FLUORINE is the most electronegative atom.

Question 22

2 atoms that have similar electronegativity will form _______ covalent bonds

Answer 22

non-polar covalent bonds (electrons are shared equally between atoms)

Question 23

2 atoms that have different electronegativity will form _____ covalent bonds

Answer 23

polar covalent bonds (electrons are not shared equally)

Question 24

2 types of covalent structures:

Answer 24

• simple covalent molecules
• giant covalent structures

Question 25

Describe the structure of simple covalent molecules.

Answer 25

- have a countable number of atoms in a fixed ratio. - within each molecule, atoms are held together by strong covalent bonds - molecules are held together by weak intermolecular forces of attraction

Question 26

Examples of simple covalent molecules:

Answer 26

methane ammonia water iodine

Question 27

Describe the structure of giant covalent structures.

Answer 27

A network of strong covalent bonds between molecules that extend throughout the structure.

Question 28

Examples of giant covalent structures:

Answer 28

diamond, graphite, silicon, silicon dioxide

Question 29

What is metallic bonding?

Answer 29

The **mutual electrostatic attraction** between **positively charged metal ions** and the **“sea" of delocalised electrons**.

Question 30

Metallic bonding results in the formation of?

Answer 30

A **giant metallic structure** where **positive ions are surrounded by a "sea" of delocalised electrons** and are **held closely together** by **strong electrostatic forces**.