Atoms And Isotopes

Question 1

Give an approximation for the radius of an atom?

Answer 1

1x10^-10 metres

Question 2

What are the three subatomic constituents of an atom?

Answer 2

Proton
Neutron
Electron

Question 3

Where is most of the mass of an atom concentrated?

Answer 3

Nucleus

Question 4

Approximately what proportion of the total radius of an atom is the radius of the nucleus?

Answer 4

1/10,000

Question 5

Describe the arrangement of protons, neutrons and electrons in an atom?

Answer 5

Protons and neutrons are found in the atoms nucleus
The electrons are found in discrete energy levels around the nucleus

Question 6

What type of charge does the nucleus of an atom have? Why?

Answer 6

Positive charge
Nucleus contains protons and neutrons
Protons have positive charge
Neutrons have no charge

Question 7

Give two ways that an atoms electron arrangement can be changed?

Answer 7

Absorbing em radiation
Emitting em radiation

Question 8

Explain how an atoms electron arrangement changes when it absorbs em radiation?

Answer 8

Electrons move further away from the nucleus
They move to a higher energy level

Question 9

Explain how an atoms electron arrangement changes when it emits em radiation?

Answer 9

Electrons move closer to nucleus
They move to a lower energy level

Question 10

How does the ratio of electrons to protons in an atom result in the atom having no overall charge?

Answer 10

Number of protons and neutrons are equal
Protons and electrons have equal and opposite charges, so charges cancel out

Question 11

What do all forms of the same element have in common?

Answer 11

All have the same number of protons

Question 12

What is the name given to the number of protons in an atom?

Answer 12

Atomic number

Question 13

What is an atoms mass number?

Answer 13

Total number of protons and neutrons in the atoms electron arrangement

Question 14

What is an isotope of an atom?

Answer 14

An atom of an element that has a different number of neutrons but the same number of protons

Question 15

How do atoms turn into positive ions?

Answer 15

Lose one or more of their outer electrons
Electrons are negatively charged so the resultant charge of the atom is positive

Question 16

What may lead to a scientific model being changed or replaced?

Answer 16

The discovery of new experimental evidence which doesn’t agree with the existing theory

Question 17

How did the plum pudding model describe the atom?

Answer 17

A ball of positive charge, with negatively charged electrons distributed evenly throughout it

Question 18

Prior to the discovery of the electron what was believed about the atom?

Answer 18

Atom was believed to be invisible

Question 19

Which experiment led to the plum pudding model being discarded?

Answer 19

Rutherford alpha scattering experiment

Question 20

What is the name given to the currently accepted model of the atom?

Answer 20

The Bohr nuclear model

Question 21

State the conclusions of the alpha- scattering experiment

Answer 21

Most of the mass of the atom is concentrated at the center in the nucleus
The nucleus is positively charged

Question 22

What reinforces a scientific theory?

Answer 22

When experimental results agree with the hypothesised theoretical calculations and theories

Question 23

What did James Chadwick’s experiments on the atom prove?

Answer 23

The existence of neutrons