C1 - Atomic Structure

Question 1

What is an element?

Answer 1

An element is a substance that is made up of only one type of atom.

Question 2

What is a compound?

Answer 2

A compound is a substance that is made up of multiple different types of atoms that are chemically bonded.

Question 3

What is the ratio of Hydrogen to Oxygen in pure water?

Answer 3

water is H₂O, so the ratio of Hydrogen : Oxygen is 2 : 1

Question 4

What are the reactants and the products in a chemical equation?

Answer 4

Reactants - substance(s) that are started with
Products - new substance(s) made

Question 5

What is the meaning of a balanced equation?

Answer 5

When the same amount and type of atoms are on each side of the equation.

Question 6

What is the Law of Conservation of Mass?

in reference to chemical reactions

Answer 6

The total mass of the products formed in a reaction is equal to the total mass of the reactants.

Question 7

List all four state symbols

Answer 7

1. soilds (s)
2. gases (g)
3. liquids (l)
4. aqueous solution (aq)

aqueous solution- substances dissolved in water

Question 8

Add state symbols to these:
1. O
2. H₂O
3. Li

Answer 8

1. O (g)
2. H₂O (l)
3. Li (s)

Question 9

Balance this equation:
H₂ + O₂ ➜ H₂O

Answer 9

2H₂ + O₂ ➜ 2H₂O

The ammount of atoms on each side is balanced, there are 4 H atoms, and 2 O atoms

tutorial video

Question 10

Balance these equations:
1. KNO₃ ➜ KNO₂ + O₂
2. Li + O₂ ➜ Li₂O
3. Fe + O₂ ➜ Fe₂O₃
4. Fe₂O₃ + CO ➜ Fe + CO₂

Answer 10

1. 2KNO₃ ➜ 2KNO₂ + O₂
2. 4Li + O₂ ➜ 2Li₂O
3. 4Fe + 3O₂ ➜ 2Fe₂O₃
4. Fe₂O₃ + 3CO ➜ 2Fe + 3CO₂

Question 11

list the 5 processes to separate mixtures

Answer 11

• chromatography
• crystallisation
• filtration
• simple distillation
• fractional distillation

Question 12

define ion

Answer 12

a charged atom that has gained or lost electrons

Question 13

define isotope

Answer 13

an atom with a different amount of neutrons

Question 14

define atom

Answer 14

the smallest part of an element that can still be recognised as that element

Question 15

list the 3 subatomic particles including their mass and their charge

Answer 15

• electron | mass 0 | charge 1-
• proton | mass 1 | charge 1+
• neutron | mass 1 | charge 0

Question 16

define element

Answer 16

a substance made up of only one type of atom

Question 17

define aqueous solution

Answer 17

mixture made by a substance dissolved in water

Question 18

list the 5 scientists who changed the atomic model and their theory

Answer 18

1. John Dalton - ‘solid spheres’
2. JJ Thompson - ‘plum pudding model’
3. Ernest Rutherford - atoms empty, tiny positive nucleus, electrons in a cloud
4. Niels Bohr - electrons in energy shells around nucleus
5. James Chadwick - nucleus consists of protons (positive) and neutrons (neutral)

Question 19

describe Rutherford’s gold foil experiment

Answer 19

1. Positively charged alpha particles were shot through a slit at a thin gold foil (a couple of atoms wide)
2. a detecting screen was placed around the gold foil to detect where the alpha particles
3. Alpha particles should have either gone straight through the foil or were all reflected backwards
4. most particles were detected going straight through however there were some deflected at large angles and even some that were bounced backwards