End of Term 2 Test Flashcards
What is an Isotope
Atoms of an element that have the same number of protons but a different number of neutrons in the nucleus.
For example, carbon atoms have 6 neutrons in their nucleus, but some have 7 and some have 8
Radioactive decay of isotopes
Some isotopes become unstable when the ratio of neutrons to protons is too high,
they may undergo radioactive decay to become more stable.
There are 3 types of radioactive or nuclear decay: Alpha Decay, Beta Decay, Gamma radiation
Alpha Decay
Symbol: a
Nucleus ejects an alpha particle (contains 2 neutrons and 2 protons – similar to a helium atom), occurs in an atom with very heavy nuclei
- Can be stopped/penetrated by a piece of paper
Uses: Many smoke detectors contain americium-241, which releases alpha radiation and helps detect smoke.
Penetration power: Low energy
Beta Decay
Symbol: B
Nucleus ejects a beta particle (1 electron)
- Can be stopped/penetrated by aluminium foil
Uses: Beta-radiation emitters can be used as cancer treatment
Penetration power: High energy
Gamma radiation
Symbol: Y High energy electromagnetic rays released from the nucleus - Can be stopped/penetrated by lead Uses: sterilise medical equipment Penetration power: High energy
Electron shell diagrams
2 electrons in the first shell
8 in the second shell
up to calcium 8, above calcium 18 in the third shell
32 in the fourth shell
Protons
Positively Charged (+1), In the nucleus, relative mass 1
Neutrons
Neutral, In the nucleus, relative mass 1
Electrons
Negatively Charged, Around the nucleus, 1/1840
What does a PH scale/ Universal indicator do?
A scale that measures the acidity to find an acid or a base
What colour does litmus paper become when met with an acidic solution
Red
What colour does litmus paper become when met with a base solution
Blue
Between what rating are Bases on the Ph scale
8-14
Between what ratings are Acids on the Ph scale
0-6
What rating is neutral on the Ph scale
7