this is a document i made from scratch using free science lessons, so everything on this document is completely correct and this document helped me get a 9-8 in combined science since i did my GCSEs in 2024.
Atoms have a radius of 0.1 nanometers. That is 1 x 10^-10.
An image of an atom is:
The nucleus:
- The middle of the atom
- Contains the proton and neutron
- Positive charge because of the proton
- Radius: 1 x 10^-14
,The electron:
- In the shells outside the nucleus
- Negatively charged
- Virtually no mass
The number of protons equals the number of electrons.
Atoms are neutral - they have no charge
The charge of electrons is negative, and the charge of protons are positive
so they cancel out and the overall charge is neutral.
In an ion (atom or group of atoms that have losed or gained electrons), the
protons must equal to the electrons. This means it HAS an overall charge.
Atomic number and mass number describes an atom.
The atomic number tell you how many protons there are
The mass number tells you how many protons and neutrons there are.
To get neutrons alone, you do: atomic number - mass number.
, element:
A substance that is made of only one sort of atom is called an element
It's the number of protons that decides what type of atom it is
Eg: 1 proton = hydrogen
So all the atoms of a particular element have the same number of protons and
different elements have atoms with different numbers of protons.
Isotopes: different forms of the same element, which have the same
number of protons but a different number of neutrons.
variation in the number of neutrons in the nuclei of atoms that gives rise to
isotopes
So isotopes have the same atomic number but different mass numbers.
Eg:
Carbon-12 and carbon-14 have the same atomic number, but different mass
number.
Many elements can exist with different isotopes.
You can find the relative atomic masses of an element:
Eg: copper has 2 isotopes. B-10 has an abundance of 20% and B-11 has
80%. Calculate the relative atomic mass
(10 x 20)#(11 x 80) / 100 = 10.8
Compound:
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