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What do atoms contain?
3 subatomic particles - protons, Neutrons and Electrons
What are protons?
Heavy and positively charged, with a relative mass of 1
What are neutrons?
Heavy and neutral, with a relative mass of 1
What are electrons?
Have hardly any mass (0.0005 - so small that it’s sometimes given as zero) and are negatively charged
What is the nucleus?
It’s in the middle of the atom and contains protons and neutrons. It has a positive charge due to the protons and almost the whole mas of the atom is concentrated in the nucleus. Compared to the overall size of the atom, it’s tiny.
How do electrons move?
In electron shells
Why is an atom neutral?
The charge of the protons (they’re both the same size) is opposite to charge of the electrons so they cancel out
What is an ion?
An atom or group of atoms that has lost or gained electrons
Why is an ion charged?
The number of protons and electrons aren’t equal, meaning it has an overall charge
What does the nuclear symbol on the periodic table represent?
It tells you its atomic (proton) number and mass number
What does the atomic number on the periodic table represent?
It tells you how many protons (and electrons since they’re equal) an atom has - every atom of an element has the same number of protons
What does the mass number on the periodic table represent?
It tells you the total number of protons and neutrons in the atom and its ALWAYS the bigger number
How do you work out the number of neutrons in an atom?
Subtract the atomic number from the mass number
