1What's an atom?
A positively charged nucleus containing portons and neutrons, surrounded by negatively charged electrons. The nucleus is much smaller than the rest of the atom but contains most the mass
2Define isotope
atoms with the same number of protons but different number of neutrons
3What's the Z number?
The mass number. Protons+Neutrons
4What's the A number?
The atomic number. The amount of protons
5What's the X number?
The symbol of the element
6How are isotopes different?
They have a different number of neutrons
11Charge of an electron
-1
12Mass of an electron
negligible (1/1857)
13Why is an atom neutral?
They have equal number of protons and electrons. Protons have +1 charge and electrons have a -1 charge s o they balance each other out
14Where are elctrons located?
They orbit the nucleus at different distances
15Why do electrons change shells?
When the atom absorbs energy, the electrons jump to higher shells
When the electron falls down an electron shell, it emits electromagnetic radiation
16How do atoms become positive ions?
They lose outer shell electrons
17What's an ion?
An atom with a positive or negative charge due to the loss of electrons
18What's an unstable nuclei?
An atom can only be stable when it has the same number of protons and neutrons
19What happens when an atom is unstable and undergoes radioactive decay?
It emits gamma radiation so the atom loses energy and becomes more stable. This is a random process
20What's the plum pudding model?
After discovering the electron, Thompson said and atom was a cloud of positive charge with negative charged electrons dotted throughout.
21What's Rutherford's experiment?
They directed alpha particles at a gold leaf, thinking it would pass straight through the space. Instead, only some reached the gold, others deflected at an angle and others deflected straight
22What's Rutherford's model?
After his experiment, he concluded there must be a lot of free space, a positively charged nucleus where most the atom's mass is
23What's the Bohr Model?
Bohr then put the electrons in a fixed space, in electron shells
24What's emitted from an atom during decay?
Different types of ionising radiation: beta minus, beta plus (positron) and gamma rays
25What is ionising radiation?
radiation that knocks electrons off atoms
26What is background radiation?
The low-level radiation that's around us all the time
27What are the origins of background radiation?
Radon gas from rocks and soil which builds up in houses, nuclear industry, medical x rays, food
28How to detect radiation
With photographic film that gets darker and darker as more radiation reaches it
29How to measure radiation
Geiger counter/tube. Radiation passes through the tube and ionises the gas in it and allows short pulses of current to flow. The counter attached counts these pulses.
30What is an alpha particle?
Two neutrons and two protons, the same as a helium nucleus
31What is a beta particle?
an electron emitted from the nucleus
32What is a gamma ray?
electromagnetic radiation
33How much do alpha particles make the mass number change by?
-4
34How much do alpha particles change the atomic number?
-2
35How are alpha particles be written?
4
He
2
36How much do beta minus' mass number change by?
0
37How much do beta minus' atomic mass change by?
+1
38How are beta minus' written?
0
e
-1
39How much do beta plus's mass number change by?
0
40How much do beta plus's atomic number change by?
-1
41How are beta plus' written?
0
e
+1
42How much do gamma rays change the atomic number by?
0
43How much do gamma rays change the mass number by?
0
44How are gamma rays written?
y
45How much does neutron emmission change the atomic number by?
0
46How much does neutron emission change the mass number by?
-1
47What's alpha particle's penetrating power?
Skin or paper
48What's alpha particle ionising power?
High
49What's beta's penetrating power?
3mm aluminium foil
50What's beta's ionising power?
Low
51What's gamma radiation's penetrating power?
Lead/ concrete
52What's gammas radiation's ionising power
very low
53What is beta minus decay?
Neutron becoming a proton, high energy electron ejected from nucleus.
54What is beta plus decay?
proton decays into a neutron and a positron
Define ion