FINAL Topic 2.1 - The Nuclear Atom

Question 1

define “element”

Answer 1

a substance that cannot be broken down into simpler substances

Question 2

define “atom”

Answer 2

the smallest unit of an element

Question 3

define “compound”

Answer 3

a substance made of two or more different elements that are chemically combined and have different properties from its constituent elements

Question 4

example of a compound

Answer 4

compound for water =

2 hydrogen atoms + 1 oxygen atom =
1 compound molecule of water

Question 5

Describe Rutherford’s discovery

Answer 5

• he shot alpha particles through a sheet of gold foil
• the alpha particles have a positive charge
• most of the particles went straight through, however, some of them repelled and bounced off an angle
• this reveals that most of the atom is empty space, however, when it collided with the nucleus (positively charged), it repelled

Question 6

atoms are made up of sub-atomic particles including

Answer 6

protons, neutrons = nucleons
electrons = outside nucleus

• protons and electrons have an equal charge +1, -1

Question 7

why are atoms neutral

Answer 7

the electrostatic attraction between oppositely charged sub-atomic particles prevents the electron from leaving the atom.

*number of protons (positive) = number of electrons (negative)

Question 8

why are neutrons important

Answer 8

otherwise the positively charged protons would repel each other and the nucleus would collapse

Question 9

where is the mass of an atom

Answer 9

majority in the nucleus as protons and neutrons are roughly 18000 times heavier than electrons

Question 10

what is the atomic number

Answer 10

number of protons/electrons

Question 11

what is the number of neutrons

Answer 11

atomic mass - atomic number
= mass of nucleus - number of protons

Question 12

What are isotopes

Answer 12

atoms of the same element with a different number of neutrons and therefore a different mass

Question 13

what are the difference between atoms and isotopes

Answer 13

the chemical properties stay the same because these are determined by the valence electrons

the physical properties differ because of the difference in mass

Question 14

why is the atomic number important

Answer 14

it never changes and is a fixed characteristic of an element, which identifies the element

Question 15

what are ions

Answer 15

when an atom loses or gains electrons to become electrically charged particles

Question 16

why do atoms form ions

Answer 16

to become stable with a full valence shell

Question 17

What happens when an atom loses electrons

Answer 17

positive ion = cation (more protons with a positive charge)

Question 18

What happens when an atoms gains electrons

Answer 18

negative ion = anion (more electrons with a negative charge)

Question 19

what is relative atomic mass of an element

Answer 19

the average mass of an atom of the element, taking into account all its isotopes and their relative abundance

Question 20

what do you use to measure the mass of individual atoms

Answer 20

mass spectrometer

Question 21

what does a mass spectrometer do

Answer 21

separates individual isotopes from a sample of atoms and determines the mass of each isotope

Question 22

what is relative isotope abundance

Answer 22

% of an isotope of an element as it occurs

Question 23

how to determine the relative atomic mass

Answer 23

(mass x abundance) + (mass x abundance) / 100

Question 24

how is the analysis by the mass spectrometer presented in

Answer 24

mass spectrum