AS-Level Chemistry: Unit 1:The Atom - created from Mind Map

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The Structure of an Atom

atoms form everything in our universe.

They consist of three particles: the proton, neutron and electron.

electrons have a -1 charge.

protons have a +1 charge

neutrons don't have a charge!

electrons 'whizz' around the nucleus of the atom in 'orbitals'.

their (electrons) relative mass is: 1/2000

(proton) Relative mass: 1

(neutron) Relative mass: 1

Nuclear Symbols

you can work out the no. of protons, neutrons and electrons from the nuclear symbol

mass number: the number of protons and neutrons in the atom's nucleus

atomic (proton) number: number of protons in the atom.

all atoms of the same element have the same proton number!

Atoms and Ions

neutral atoms (no charge) have the same electron and proton number.

the neutron number is just the mass no. minus the atomic no., i.e. "the top minus the bottom" (Nuclear Symbols)

Ions have different no. of protons and electrons.

Negative ions (e.g. Br-) have more electrons than protons.

Positive ions (e.g. Mg2+) have more protons than electrons.

Exam Tip: Ions

Ions are easy to spot: they always have a plus or minus charge (+ or -) next to them! If the charge is a plus, it means an electron has been lost, e.g. Mg2+ means that the Magnesium ion has lost two electrons. If there is a minus sign, it means electrons have been gained. For example, 3- means 3 electrons have been lost!

Isotopes

isotope isn't just a scary science word, nope! Isotopes of an element are atoms with the same proton no., but different neutron number.

basically atoms with the same no. of protons but different neutron no. are isotopes.

different isotopes of the same element react (chemically) the same way

AS-Level Chemistry: Unit 1:The Atom