Bonding

Question 1

Metallic bonding

Answer 1

A lattice of positively charged ions (cations), surrounded by free- moving,‘delocalised’ electrons.

Question 2

Properties of metallic bonding

Answer 2

Because of their structure and bonding, Metals are:
•Good conductors of electricity WHEN SOLID
•Good conductors of heat
•Malleable and Ductile
•High boiling points
•Hard and dense

Question 3

Galvanising

Answer 3

The process of applying a protective zinc coating to steel or iron to prevent rusting

•prevents corrosive substance from reaching iron / steel and zinc corrodes first

Question 4

Cation

Answer 4

Positively charged ion

Question 5

Anion

Answer 5

Negatively charged ion

Question 6

Ionic bond

Answer 6

• Ionic bonding occurs as the result of a metal atom donating its outer shell electrons to a non-metal atom.
• The metal becomes a Cation.
• The non-metal becomes an anion.

Question 7

Properties of ionic compounds

Answer 7

• high melting and boiling points
• hard and brittle
• can only conduct electricity as molten
• arranged in an ionic lattice

Question 8

Why are ionic solids brittle?

Answer 8

when distorted like charged ions move closer to each other and strong electrostatic repulsion shatter the solid.

Question 9

Why ionic liquids (molten and solution) can conduct electricity

Answer 9

Because ions are free to move and carry a charge when not in a lattice

Question 10

Why ionic compounds have high melting and boiling points?

Answer 10

Due to the strong ionic bonds in 3 dimensions which requires great amounts of energy to overcome the bonds.

Question 11

Covalent bonding

Answer 11

when non metallic atoms combine to form either molecules or covalent lattices with the sharing of electrons

Question 12

Dative covalent bond

Answer 12

a covalent bond in which both of the shared electrons are contributed by one atom only

Question 13

Valence structure

Answer 13

These show bonds in the form of lines, with other outer shell electrons as dots. Single bonds have single lines
Double bonds have 2 lines
Triple bonds have 3 lines

Question 14

Lewis Structure (Electron Dot Diagram

Answer 14

These show outer-shell electrons and shows how they share to form a bond.

Question 15

Octet rule

Answer 15

atoms with an atomic number below 20 tend to combine so that they each have eight electrons in their valence shells, making the same electronic configuration as a noble gas.

Question 16

Valence electrons

Answer 16

The electrons in the outermost (valence) principal energy level of an atom that can participate in the formation of chemical bonds with other atoms.

Question 17

Atomic number

Answer 17

The number of protons in an atom which determines its chemical properties.

Question 18

Mass number

Answer 18

Number of protons and neutrons in an atom

Question 19

Expanded octet

Answer 19

A case where an atom shares more than eight electrons with its bonding partners.
•elements in period 3 group 5-7 can have greater than 8 electrons in valence shell

Question 20

Electron pair repulsion theory

Answer 20

the shape of a molecule is determined by the number of electron pairs surrounding the central atom

•electrons repel and therefore arrange away from one another

Question 21

Covalent networks

Answer 21

are non-metal substances that exist as giant, 3D arrays of atoms.
-graphite, diamond, silicon dioxide

Question 22

Properties of covalent molecules

Answer 22

• Have low melting/boiling points - do not conduct electricity (no free moving electrons)
• have low solubility in water**

**there are a few exceptions i.e NH3, CH3COOH

Question 23

Properties of covalent networks

Answer 23

• high melting and boiling point
• non-conductors of electricity (except Graphite) or heat
• very hard substances
• insoluble in water

Question 24

Properties of diamond

Answer 24

• Giant lattice of carbon atoms covalently bonded to 4 others in tetrahedral arrangement
• high melting and boiling points
• does not conduct electricity
• insoluble in water

Question 25

Properties of silicon dioxide

Answer 25

* arranged tetrahedrally with each oxygen covalently bonded to 2 silicon atoms * high melting point * does not conduct electricity * insoluble in water

Question 26

Properties of graphite

Answer 26

* Each C atom is joined to three others to form hexagonal layers * has a high melting point * is insoluble in water * it is soft * it conducts electricity

Question 27

Why is graphite a conductor and soft

Answer 27

* The spare electron becomes delocalised between the layers * These mobile electrons enable graphite to conduct electricity * The graphite layers can slide over one another, making graphite soft and slippery

Question 28

Allotropes

Answer 28

Molecules with different structural arrangements with different properties - diamond, graphite (C)

Question 29

Types of intermolecular forces

Answer 29

* Dispersion Forces * Dipole / dipole attraction * Hydrogen Bonding

Question 30

Dispersion forces

Answer 30

Between all substances due to the constant movement of electrons.This gives rise to electrostatic forces of attraction. The electrons around a covalent bond are constantly moving and will form temporary dipole attraction • very weak

Question 31

Dipole-Dipole forces

Answer 31

When there is a difference in electronegativity between two atoms in a molecule, a permanent dipole is created

Question 32

Hydrogen bond

Answer 32

This is a dipole-dipole attraction that occurs between molecules with Hydrogen bonded to a “NOF’ and attracted to a “NOF”

Question 33

Polar bond

Answer 33

A bond resulting from an uneven sharing of electrons between two atoms.

Question 34

Polar molecule

Answer 34

Polar molecules arise when the intramolecular bonds are polar. If the molecule is asymetrical then a polar molecule will be formed since there is an overall uneven distribution of charge.