T4 atoms and isotopes

Question 1

give an approximation for the radius of an atom

Answer 1

1x10^-10 metres

Question 2

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

in the 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 atom’s nucleus

- 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 a positive charge
• neutrons have no charge

Question 7

give 2 ways that an atom’s electron arrangement can be changed

Answer 7

1. absorbing electromagnetic radiation

2. emitting electromagnetic radiation

Question 8

explain how an atom’s electron arrangement changes when it absorbs EM radiation

Answer 8

• electrons move further away from the nucleus

- move to a higher energy level

Question 9

explain how an atom’s electron arrangement changes when it emits EM radiation

Answer 9

• electrons move closer to the nucleus

- 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 is equal to the number of electrons

- protons and electrons have equal and opposite charges, so charge cancels

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 atom’s mass number

Answer 13

total number of protons and neutrons in the atom

Question 14

what is an isotope of an atom

Answer 14

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

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 indivisible

Question 19

which experiment led to the plum-pudding model being discarded

Answer 19

Rutherford’s alpha-scattering experiment

Question 20

name given to the currently accepted model of the atom

Answer 20

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 centre in the nucleus
• nucleus is positively charged

Question 22

what did James Chadwick’s experiments on the atom prove

Answer 22

existence of neutrons

Question 23

what reinforces a scientific theory

Answer 23

when experimental results agree with the hypothesised theoretical calculations and theories