defination

Question 1

Describe relative atomic mass, Ar

Answer 1

The average mass of the isotopes of an element compared to 1/12th of the mass of an atom of 12C

Question 2

2 Define relative molecular mass, Mr ,

Answer 2

the sum of the relative atomic masses.

Question 3

Describe how paper chromatography is used to separate mixtures of soluble colourless substances

Answer 3

using a suitable solvent and a locating agent

Question 4

State and use the equation for Rf

Answer 4

Rf = distance travelled by substance / distance travelled by solvent

Question 5

Elements:

Answer 5

Pure substances made of only one type of atom.

Question 6

Compounds:

Answer 6

Substances composed of two or more elements chemically combined

Question 7

Mixtures:

Answer 7

Combinations of two or more substances that are physically mixed and can be separated by physical means

Question 8

Isotopes

Answer 8

different atoms of the same element that have the same number of protons but different numbers of neutrons

Question 9

proton number/ atomic number

Answer 9

the number of protons in the nucleus of an atom

Question 10

mass number/nucleon number

Answer 10

the total number of protons and neutrons in the nucleus of an atom

Question 11

ionic bond (metal+non-metal)

Answer 11

a strong electrostatic attraction between oppositely charged ions

Question 12

cations

Answer 12

An atom or groups of atoms with a positive charge

Question 13

anion

Answer 13

An atom or groups of atoms with a negative charge

Question 14

the properties of ionic compounds:

Answer 14

(a) high melting points and boiling points (ions attracted by strong electrostatic forces which require large amounts of energy to overcome)
(b) good electrical conductivity when aqueous or molten and poor when solid (cause ions are free to move when aq or mol)

Question 15

the giant lattice structure of ionic compounds

Answer 15

The regular arrangement of alternating positive and negative ions

Question 16

covalent bond (non-metal + non-metal)

Answer 16

forms when a pair of electrons is shared between two atoms leading to noble gas electronic configurations

Question 17

properties of SIMPLE molecular compounds (covalent compounds):

Answer 17

(a) low melting points and boiling points (weak intermolecular forces (forces between molecules) only require a small amount of energy to break)

(b) poor electrical conductivity (No free electrons or ions present to carry an electrical current)

(c) have strong covalent bonds (covalent bonds between atoms are very strong)

Question 18

metallic bonding

Answer 18

the electrostatic attraction between the positive ions in a giant metallic lattice and a ‘sea’ of delocalised electrons

Question 19

Properties of Metallic Bonding

Answer 19

1. Good electrical conductivity: Delocalised electrons can move through the structures and carry current.
2. High Melting and Boiling Point: More energy to overcome strong forces of attraction between positive metal ions and the sea of delocalised electrons and vibrate/transfer heat
3. malleable Malleability: Can be hammered into shapes as layers can slide over each other.
4. ductile Ductility: Can be drawn into thin wires