C1 - Particles

Question 1

What do chemists mean when they use the term particles?

Answer 1

Atoms, ions or molecules

Question 2

What is the arrangement of a solid?

Answer 2

regular

Question 3

what is the arrangement of a liquid?

Answer 3

random

Question 4

what is the arrangement of a gas?

Answer 4

random

Question 5

what is the relative distance between solid particles?

Answer 5

very close

Question 6

what is the relative distance between liquid particles?

Answer 6

close

Question 7

what is the relative distance between gas particles?

Answer 7

far apart

Question 8

what is the main movement of solid particles?

Answer 8

they vibrate around fixed positions

Question 9

what is the main movement of liquid particles?

Answer 9

they move around each other

Question 10

what is the main movement of gas particles?

Answer 10

they move quickly in all directions

Question 11

can you compress a substance in its solid state?

Answer 11

no

Question 12

why can you not compress a solid or liquid substance?

Answer 12

there is no space for the particles to move into

Question 13

why do substances in a solid state have a fixed shape?

Answer 13

since it’s particles vibrate around fixed particles and cannot move from place to place

Question 14

Give 3 examples of chemical changes

Answer 14

• cooking eggs
• steel rusting
• wood burning
• acid + alkali

Question 15

Give 3 examples of physical changes

Answer 15

• freezing juice to make a lolly
• mixing sand with water
• dissolving sugar in water

Question 16

What happens to a substance when it changes state?

Answer 16

The substance’s particles stay the same but the movement and arrangement changes

Question 17

What happens to a substance’s particles during a chemical reaction?

Answer 17

Particles break up and join in different ways

new substances are made

Question 18

What is the smallest particle that makes up a substance?

Answer 18

atoms

Question 19

What element has the smallest atom?

Answer 19

Helium atoms

Question 20

what is the equation to calculate the mean distance between atoms?

Answer 20

distance between atoms
————
diameter of atom

Question 21

What are the forces between particles called?

Answer 21

Electrostatic forces

Question 22

State three limitations of the particle model

Answer 22

• unable to see the electrostatic forces
• unable to see the size of particles
• unable to the the space between particles

Question 23

Why does the volume of a substance increase when it melts?

Answer 23

Some of the forces of attraction are overcome and so the particles can move around each other

Question 24

describe what happens to the particles of a substance in the liquid state as it cools down but remains in the liquid state

Answer 24

• particles transfer energy its surroundings
• the particles slow down
• some some electrostatic bonds form between them

Question 25

describe what happens to the particles of a substance in the liquid state as it freezes

Answer 25

• energy transfers to its surroundings
• the particles become regularly arranged
• the particles can no longer move around each other
• more electrostatic bonds form between each other

Question 26

State one way in which the diagram does not accurately model the arrangement of particles

Answer 26

show them as stationary, and very close

Question 27

what is an atom?

Answer 27

the smallest particle of an element that still has its chemical properties

Question 28

what is a molecule?

Answer 28

• two or more atoms joined together

Question 29

what is a bond length?

Answer 29

the distance between the centres of two joined atoms

Question 30

what does the atomic number tell us?

Answer 30

how many protons there are in the atom

Question 31

what is the mass number?

Answer 31

total number of protons and neutrons

Question 32

what is an isotope?

Answer 32

• an atom of the same element with the same number of protons and electrons, but a different number of neutrons
• same atomic number
• different mass number

Question 33

what do the chemical properties of an element depend on?

Answer 33

the number of electrons in the atom

Question 34

what is an ion?

Answer 34

• a charged particle

- formed when atoms (or groups of atoms), lose or gain electrons

Question 35

how did dalton contribute to the development of the atomic model?

Answer 35

• all matter is made from atoms
• different elements have different atoms
• same elements have identical atoms

Question 36

what is a chemical bond?

Answer 36

an attractive force which keeps two atoms bonded together

Question 37

How did rutherford’s results change as he increased the deflection angle (and why?)

Answer 37

• The number of particles deflected decreased
• as the particles were not being shot straight to the middle (where the nucleus was), and instead at the side where it was empty space

Question 38

Charge of an alpha particle?

Answer 38

Positive, +2

Question 39

What Electromagnetic radiation is emitted by electrons?

Answer 39

Photon

Question 40

What is the typical diameter of atoms and small molecules?

Answer 40

0.1nm

Question 41

Define atomic number

Answer 41

The number of protons in the nucleus of an atom

Question 42

What properties do isotopes affect and don’t affect.

Answer 42

May Affect physical properties - due to different numbers of neutrons.
Do not affect chemical properties - number of electrons the same.

Question 43

What experiment did JJ Thompson do? What did he find? What did he have to make sense of?

Answer 43

He found that beams of cathode rays changed direction in electric and magnetic fields - he concluded that cathode rays were tiny particles that were negatively charged and much smaller than atoms.

He had to make sense of two observations:

• atoms contain electrons
• atoms are neutral overall