Atomic structure Flashcards

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1
Q

what is in the nucleus of an atom

A

proton and neutron

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2
Q

where do electrons orbit

A

around the shells

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3
Q

what was JJ thompson a model of the atom

A

Plum pudding model
Ball of positive charge
with negative electrons embedded in it

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4
Q

What was rutherfords alpha scattering experiment

A

Fired positively charged alpha particles at a thin sheet of gold foil
Most went straight through however some deflected and some even came straight back off the foil
From these observations he concluded that Most of the atom was empty space ( due to going straight through)
The ones that deflected showed that the nucleus was positive as opposite charges repel
The ones that came straight back told him that the mass was concentrated in the nucleus

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5
Q

what does an alpha particle consist of

A

two protons and two neutrons

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6
Q

What happens to the alpha particle when it decays

A

4
He
2

e.g alpha decay in 16
K
8
= 12
K
6

loses 4 of the mass number
loses 2 from the atomic number

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7
Q

What is a beta particle

A

Fast moving electron

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8
Q

What’s a beta particles relative mass and mass number

A

0

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9
Q

what does a beta particle look like

A

0
e
-1

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10
Q

What does beta particles do to the atomic number( bottom number) in beta decay

A

Causes the bottom number to INCREASE BY 1

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11
Q

What are gamma rays

A

Waves

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12
Q

Does gamma rays cause any change to the number when in gamma decay

A

No

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13
Q

order the 3 from most ionizing to least

A

Alpha
Beta
Gamma (as it’s a wave)

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14
Q

Order it from most penetrating to least ( reverse )

A

Gamma
Beta
Alpha

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15
Q

what is alpha particles stopped by

A

thin sheet of paper

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16
Q

What is beta particles stopped by

A

Aliminium

17
Q

What is gamma stopped by

A

Thick block of lead
as it’s the most penetrating

18
Q

What is half life

A

time taken for radioactive nuclei in a sample to halve

19
Q

what causes something to be radioactive

A

when it has unstable isotopes

20
Q

What is Radioactive decay

A

When an unstable nucleus decays into another element and gives out radiation to become more stable

21
Q

What is Activity

A

overall rate of decay of all isotopes

22
Q

What is activity measured in

A

Bq Bequerels

23
Q

Example question = the half life of a radioactive source is 40 hours. There are initially 3 million radioactive nuclei in a sample. How many nuclei will remain after 5 days

A

5 x 24h = 120h

120/ 40 = 3 half lifes

halve 3,000,000 3 times

24
Q

What is nuclear fission

A

the splitting of large unstable nuclei into smaller nuclei

25
Q

What happens in nuclear fission

A

An unstable fast moving neutron hits the unstable nuclei.
This causes the nuclei to become violently unstable and therefore split
These split into daughter nuclei
Two or three more neutrons explode out of the fission reaction and continues on

THIS IS KNOWN AS A CHAIN REACTION

26
Q

what’s nuclear fusion

A

when two small light nuclei join together to make one heavy nucleus

27
Q

Does fusion or fission Release more energy

A

FUSION