Zusammenfassung der Ressource
AS-Level Chemistry: Unit 1:The
Atom
- 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.
- electrons 'whizz' around
the nucleus of the atom
in 'orbitals'.
- their relative mass is: 1/2000
- protons have a +1
charge
- Relative mass: 1
- neutrons
don't have a
charge!
- 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
- 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