Radioactivity + Atomic Structure

Question 1

Define an alpha particle

Answer 1

A particle made of 2 protons and 2 neutrons
Emitting ionising radiation
Helium Nucleus

Question 2

Define an ion

Answer 2

Charged particles that form when an atom either gains or loses electrons

Question 3

When are negative ions created?

Answer 3

When an atom gains electrons

Question 4

When are positive ions created?

Answer 4

When an atom loses electrons

Question 5

What is the overall charge of an atom?

Answer 5

Neutral

Question 6

What is the charge of a positron?

Answer 6

+1

Question 7

What is the relative mass of a positron?

Answer 7

1/2000
(negligable)

Question 8

Name the antiparticle of an electron

Answer 8

Positron

Question 9

When can positrons be produced?

Answer 9

During nuclear beta plus decay
when a proton spontaneously changes into a neutron and a positron

Question 10

In normal conditions (not in a vacuum), how long do positrons last?

Answer 10

A fraction of a second before they react with electrons and are destroyed

Question 11

Why does the atom have a neutral charge?

Answer 11

The number of negative elctrons is equal to the number of positive protons

Question 12

What is meant by atomic number?

Answer 12

Number of protons in an atom

Question 13

What does proton number determine?

Answer 13

Which element an atom is

Question 14

What is the atomic number of Hydrogen?

Answer 14

1

Question 15

What is meant by mass number?

And what can it also be called?

Answer 15

The total number of particles within an atom’s nucleus
(protons and neutrons)
Nucleon number

Question 16

Define Isotope

Answer 16

Atoms of the same element with an equal number of protons but a different number of neutrons

Question 17

Name the 3 isotopes of hydrogen in order from fewest to most neutrons

Answer 17

Protium
Deuterium
Tritium

Question 18

True or false:
A paritcular element’s nucleus always has the same charge

Answer 18

True

Question 19

What makes some isotopes unstable?

Answer 19

An imbalance of protons and neutrons

Question 20

State an alternative name for shells

Answer 20

Energy Levels

Question 21

The higher the energy level…

Answer 21

the further the distance of the electron from the nucleus

Question 22

What happens to electrons when they absorb electromagnetic radiation?

Answer 22

They move to a higher energy level
and are exited

Question 23

What does it mean for an elctron to be exited?

Answer 23

It has moved up an energy level

Question 24

What happens as an exited electron returns to its original energy level?

Answer 24

Emits a wave of EM radiation

Question 25

Where do light waves come from?

Answer 25

Electrons moving down energy levels and emitting EM radiation

Question 26

State 3 ways in which electrons in an atom's outer energy level can be knocked out

Answer 26

Friction when objects are rubbed together Absorbing EM radiation so gaining enough energy to leave the atom Chemical reactions

Question 27

Who discovered electrons?

Answer 27

JJ Thomson

Question 28

Which model did JJ Thomson propose?

Answer 28

Plum Pudding Model

Question 29

Describe Thomson's Plum Pudding Model

Answer 29

The atom was a **positvely charged mass** (dough) with **embedded negatively charged electrons** (plums)

Question 30

Name Rutherford's experiment that helped him form his nuclear model

Answer 30

Gold Foil Experiment

Question 31

Describe the Gold Foil Experiment | inc. their expectations

Answer 31

Rutherford directed a beam of Alpha particles at a thin gold foil They expected the Alpha particles to travel straight through and maybe change direction a small amount

Question 32

State Rutherford's observations from the Gold Foil experiment

Answer 32

Most Alpha Particles passed straight through the thin gold foil (like they had predicted) Some alpha particles changed direction but continued through the foil A few alpha particles bounced back off the gold foil

Question 33

What did Rutherford discover the Plum Pudding model could not explain?

Answer 33

Why some of the alpha particles bounced back from the gold foil

Question 34

State Rutherford's 3 conclusions from his Gold Foil experiment

Answer 34

Atoms are mostly empty space The nucleus has a strong positive charge Atoms contain a small, dense nucleus

Question 35

Name Rutherford's model

Answer 35

Nuclear Model

Question 36

State features of Rutherford's nuclear model

Answer 36

Nearly all of an atoms mass is concentrated in the centre of the atom (in the nucleus) The nucleus is positively charged Negatively charged electrons orbit the nucleus at a distance

Question 37

State the additions Niels Bohr added to his model of the atom

Answer 37

Electrons orbit the nucleus at **different distances** Different orbit distances are called energy levels 2 electrons orbit in the first energy level 8 electrons orbit in the second and third energy levels

Question 38

Why was the Bohr model accepted?

Answer 38

It could explain findings from other experiments better than the Nuclear Model It could explain the processes of absorption and emission of EM radiation

Question 39

What is the radius of an atom?

Answer 39

1 x 10 ^ -10 m