2. Atoms, elements and compounds

Question 1

Ion

Answer 1

A positively or negatively charged particle formed by the loss or gain of electrons.

Question 2

Atom

Answer 2

A neutral particle composed of protons, neutrons and electrons.

Question 3

Electron

Answer 3

Subatomic negatively charged particles that orbit the nucleus of an atom. Mass = 0, Electrons = Atomic Number 2.8.8.2

Question 4

Neutrons

Answer 4

Subatomic particles with no charge. Found in the nucleus. Mass = 1, Neutrons = Atomic mass - Atomic number.

Question 5

Element

Answer 5

A chemical substance that cannot be broken down into simpler substances. It is composed of one type of atom only.

Question 6

Anion

Answer 6

A negatively charged ion.

Question 7

Cation

Answer 7

A positively charged ion.

Question 8

Period

Answer 8

Row in the periodic table. Period number = Number of occupied electron shells.

Question 9

Mixture

Answer 9

Two or more chemical substances found together but no chemically bonded.

Question 10

Group

Answer 10

Column in the periodic table. Group number = Number of electrons in the outer shell (exception helium)

Question 11

Protons

Answer 11

Positively charged subatomic particle found in the nucleus of an atom. Mass = 1, Protons = Atomic number.

Question 12

Covalent bond

Answer 12

A force of attraction between shared pairs of electrons and the nuclei of two atoms.

Question 13

Organic compound

Answer 13

A substance consisting of carbon and one or more other elements, joined together by covalent bonds.

Question 14

Natural Gas

Answer 14

Gas that people burn for energy (Methane).

Question 15

Alkane

Answer 15

An organic compound containing only single C–C and C–H bonds.

Question 16

Alkene

Answer 16

An organic compound containing one or more C=C double bonds.

Question 17

Alcohol

Answer 17

An organic compound that contains an OH functional group.

Question 18

but

Answer 18

C₄

Question 19

meth

Answer 19

C

Question 20

eth

Answer 20

C₂

Question 21

prop

Answer 21

C₃

Question 22

ane

Answer 22

single bonds + alkane

Question 23

ene

Answer 23

double bonds + alkene

Question 24

anol

Answer 24

OH + alcohol

Question 25

Alkene (General Formula)

Answer 25

CₙH₂ₙ

Question 26

Alcohol (General Formula)

Answer 26

CₙH₂ₙ₊₁OH

Question 27

Alkane (General Formula)

Answer 27

CₙH₂ₙ₊₂

Question 28

Triple Bond

Answer 28

A covalent bond in which three pairs of electrons are shared.

Question 29

Double Bond

Answer 29

A covalent bond in which two pairs of electrons are shared.

Question 30

Single Bond

Answer 30

A covalent bond in which one pair of electrons are shared.

Question 31

Macromolecule

Answer 31

A giant molecule created by atoms covalently bonded to one another.

Question 32

Allotropes

Answer 32

Alternative forms of an elemental substance. For example, diamond and graphite are allotropes of carbon.

Question 33

Delocalised

Answer 33

Electrons that are not associated with a particular atom.

Question 34

Intermolecular forces

Answer 34

The weak force of attraction that holds molecules close together

Question 35

Volatility

Answer 35

The property of a material describing how easily it vaporises (evaporates).

Question 36

Covalent Molecules (Properties)

Answer 36

1. They have weak intermolecular forces
2. Extremely volatile (bonds break easily)
3. Often soluble in water or other solvents (eg. alcohol)
4. Poor conductors of electricity in any form
5. Low melting points

Question 37

Ionic compounds (Properties)

Answer 37

1. Strong ionic bonds.
2. High melting points / Not volatile (Difficult to break bonds)
3. Do not conduct when solid.
4. Conduct electricity when in solution (for a while)

Question 38

Diamond

Answer 38

• Each carbon atom makes 4 covalent bonds
• Regular arrangement
• High melting point - bc strong covalent bonds require ~ 4000 celsius to break.
• Hardest natural substance - 10 on the mohs scale thus used in large industrial drills.

Question 39

Silicon Dioxide

Answer 39

• Qaurtz/Sand
• Each silicon atom makes 4 bonds with one oxyen atom
• 3D lattice of atoms
• Very similar structure to diamond
• Very high melting point - bc of strong covalent bonds require lots of energy to break

Question 40

Graphite

Answer 40

• Each carbon atom makes 3 strong covalent bonds with other carbon atoms
• Creates sheets of hexagonally arranged carbon atoms - one sheet is called graphene
• Weak intermolecular force between sheets holding them together - sheets can slide on each other (forces between sheets break easily) - Graphite dust used as lubricant in machines between gears etc.
• Good conductor - used to make electrodes - bc 4th valence electron is free (delocalised) and carries current around the layer.