Year 9 ‘INSIDE the ATOM’

Key Concepts

Class notes

SCIENCE UNDERSTANDING

  • All matter is made of atoms which are composed of protons, neutrons and electrons; natural radioactivity arises from the decay of nuclei in atoms.

Elaborations

  • Describing and modelling the structure of atoms in terms of the nucleus, protons, neutrons and electrons
  • Comparing the mass and charge of protons, neutrons and electrons
  • Describing in simple terms how alpha and beta particles and gamma radiation are released
from unstable atoms

NAME:


Timing 8 lessons

Science Quest
TEXTBOOK
SCIENCE Quest PRACTICALS / ACTIVITIES
SCIENCE Quest
HOMEWORK
OTHER ACTIVITIES/RESOURCES

1
6 Inside the Atom(p.255) - Introduction
Suggestions: Do you have the inside information? Complete activity with class discussion.




2&3
6.1 Science Understanding - Chemical Building Blocks (p.256)
  • describe the main features of the currently accepted model of the atom
  • identify the nucleus, protons, neutrons and electrons in a simple illustration of an atom
  • compare the mass and charge of protons, neutrons and electrons
Suggestions:
  • eLesson -Watch a video from The story of science about the development of the model of the atomeles-1775
  • Flame Colours Practical – to investigate the relationship between energy levels in atoms and the arrangement of electrons around the nucleus.
6.1 Chemical building blocks
6.2 How big is an atom?

Understanding & Enquiring (p. 258) Qn’s 1-8
Words to Learn
- nucleus, protons, neutrons, electrons


3
6.2 Stability and Change-
Inside the Nucleus (p.259)
  • associate different isotopes of elements with the number of neutrons in the nucleus
  • explain why, in terms of the stability of the nucleus, some isotopes are radioactive while others are not
  • represent isotopes correctly in both symbols and words
Suggestions:
  • eLesson -Smashing atoms in CERN eles - 1085

  • Use the Radioactive half-life interactivity in your eBookPLUS to choose a radioactive element and the mass, and then watch the graph of its half-life. Use the data to answer questions on the accompanying worksheet. int-1652


Good video for 'Inside the Atom' !!

https://www.youtube.com/watch?v=FSyAehMdpyI
(Crashcourse)

https://www.youtube.com/watch?v=xazQRcSCRaY
6.3 Top Ten Elements


Understanding & Enquiring (p. 258) Qn’s 1-6
Words to Learn
- isotopes, stable, unstable, radioisotopes, nuclear radiation, half-life.


5
6.3 Science as a Human Endeavour -
Using Radioactivity (p.263)
  • describe the impact of the discovery of radioactivity and the subsequent development of nuclear technology on the course of history
  • explain how radioisotopes are used in nuclear reactors, radiometric dating, the treatment of cancer, medical diagnosis and food preservation
  • examine the risks associated with radioactivity
Suggestions:

eLesson

  • § The mystery of radium
  • § Watch a video from The story of science about Marie Curie and radioactivity eles 1779

  • Nuclear medicine - Meet Dale Bailey, who works with nuclear medicine, in an episode of Catalyst from ABC TV. eles-1084
Investigation -Radiotherapy is an effective method of treating cancer. However, it has a number of side effects. Find out what the side effects are.

Radiotherapy

https://www.youtube.com/watch?v=_moypMx05Fw

Xrays - are they dangerous?
https://www.youtube.com/watch?v=vmdemMnkSKo
6.4 Putting Nuclear Energy to Use
Words to Learn
- radiometric dating, radiocarbon dating, nuclear reactors, fission


6
6. 4 The Dark Side of Radiation(p.266)
  • Investigate sites where radiation disasters have had catastrophic consequences.
Suggestions:
Investigation - Create a newspaper report on the accident at Chernobyl, Fukushima or Three Mile Island, explaining
    1. how the accident affected the workers at the power plant and the surrounding towns and villages
    2. the attempts made to reduce or control the damage caused by the radiation
    3. the long-term effects of the accident.





Assessment
- Completion of Worksheets
- Completion of one investigation from 6.3 or 6.4.
















Class Notes

The first 20 Elements

Element symbol
atomic number
atomic mass
number of electrons
number of protons
Number of neutrons
H
1
1
1
1
0
He
2
4
2
2
2
Li
3
7
2.1
3
4
Be
4
9
2.2

5
B
5
11
2.3

6
C
6
12


6
N
7
14



O
8
16



F
9
19



Ne
10
20
2.8


Na
11
23



Mg
12
24



Al
13
27



Si
14
28
2.8.4


P
15
31
2.8.5


S
16
32
2.8.6


Cl
17
35
2.8.7


Ar
18
40
2.8.8


K
19
39
2.8.8.1


Ca
20
40
2.8.8.2


Ca2+





Isotopes

They are examples of atoms of the same element but they have a different atomic mass. They have a different mass because they have more (or less) neutrons than the regular version of this atom of the element.

Examples
Carbon 14 and Carbon 12

Carbon 12 is the usual version of the atom we come across. However for every 1,000,000,000,000 carbon 12s they might be 1 carbon 14. The difference between carbon 12 and carbon 14 is the number of neutrons.

Carbon 12 has an atomic mass of 12 and an atomic number of 6 therefore it has 6 neutrons.
This is stable
Carbon 14 has anatomic mass of 14 and an atomic number of 6 therefore it has 8 neutrons.
this is radioactive

Having these extra neutrons can make it unstable and cause it to decay. When they decay the atom splits into smaller bits and forms other elements with a smaller atomic mass.

There are three different types of radiation
1 alpha particles are released from the nucleus of a large atom.
alpha particles are made of 2 neutrons and 2 protons and no electrons. They are slow moving and can be blocked by paper or skin or a lot of air.
These are Helium atoms without any electrons.
2. beta particles can be be released from a large atom and can be either negative or positive -
A beta particle is made up of a positron or an electron that has been emitted when an atom undergoes beta decay
They can not pass through metal (), they are very fast and can damage people.

3. gamma radiation - is not a particle it is an energy wave that is emitted from a high speed atom. They are very dangerous to living things and can be stopped by lead and dense concrete.

Radioactivity and "Half Life"
The time taken for half of all the nuclei in a sample of a radioisotope to disintegrate or decay is known as its half-life. This means a 1 kg mass of radioactive Strontium will decay to a smaller mass of 0.5 kg in a period of 28 years.
Because the 1 Kg mass halved (to half a Kg) in 28 years we say the half - life of Sr is 28 years.

Given this information we could expect a half kg mass of strontium to only weigh 1/8th of a kg after 56 years.

here is the working
half life = 28 yrs ( given in the question or determined from a graph)
starting mass -= 0.5kg ( for this question)
calculate - how many half lives in the time period given in the question ( ie how many 28 yr periods in 56 years or given time divided by half life) for this question 56 / 28 = 2
This means the starting mass will halve twice. 1/2 kg x 1/2 = 1/4, 1/4 x 1/2 = 1/8 kg

Uses for radioactivity
1. Radiometric dating - this uses the known half life of an element to date past living things like fossils
2. Radiotherapy - is where cancerous cells are bombarded with a radioactive emission which in turn destroys the DNA in the tumour cells stopping them from replicating and growing. It can also damage nearby cells and this can cause side effects.
3. Uses in nuclear power plants. When an isotope breaks down heat is released - this heat is used to turn water into steam and the steam turns turbines to generate electricity. The waste product of this nuclear fission (to split) is radioactive with a very long half life and as such has to be
disposed of carefully.

When Nuclear goes wrong
1 Radiation poisoning - you can get this by being exposed to a range of nuclear radiation including Gamma rays and Beta particles. The symptoms are -headaches, vomiting, nausea, diarrhoea. No cure
2. Nuclear reactors fail - -If the cooling systems of a reactor fails the core temperature can jump to 5000 degrees Celsius in under 4 seconds. This results in a meltdown. The core of the reactor can burn through the surrounding concrete and deep in to the earth. This will poison all the ground water. Or the whole thing can explode and pour radioactive dust into the atmosphere poisoning surrounding countryside farmland towns etc
3 Nuclear warfare. - this where bombs containing radioatcive material are made to explode and scatter their radioactive contents to kill the people around. There is also a sever thermal flash that vapourises everything (people and buildings) with in a 10 Km radius - depending on the size of the nuclear weapon.

How the geiger counter works
down load the file




here.

Fusion - this is a nuclear reaction in which molecules are forced to combine. This type of reaction is very common in the Sun where hydrogen atoms collide and form Helium
Screenshot 2016-06-22 09.24.24.png


Screenshot 2016-06-22 09.24.44.png


Fission - this is a radioactive reaction where a large atom is smashed by a neutron and broken into smaller atom
Screenshot 2016-06-22 09.23.00.png