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Summary CHEMISTRY CHAPTER 1 AQA
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Quick and informative summary of chapter 1 of aqa chemistry science- this is combined science!
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Historical models of the atomPlum pudding (1897, J J Thomson)-
He thought the atom consisted of positive
'dough' with a lot of negative electrons
(negative) stuck in it
Bohr’s model (1915, Niels Bohr)
electrons orbited the nucleus in different energy
levels
negatively charged electrons orbit a small,
positively charged nucleus
Chadwick and the neutron (1932, James Chadwick)
said core also contained a new uncharged
particle, which he called the neutron
Bohr and other scientists knew that there also
had to be a neutral particle the same size as a
proton to keep the nucleus stable and to make
up the mass.
Atomic number and mass number
Atomic number: is the number of
protons in an atom
Mass number: total number of neutron
and protons in an atom
Protons- atomic number
Electron- atomic number
Neutron: atomic number- mass number
Isotopes
-are the atoms of an element with different numbers of neutrons.
They have the same proton number (atomic number), but different
mass numbers (neutrons)
The relative abundance of an isotope is the percentage of atoms with
a specific atomic mass found in a naturally occurring sample of an
element.
Relative atomic mass
, Atomic Structure Relativ
Particl Relativ
e
Atoms contain three sub-atomic e e mass
charge
particles called protons, neutrons
and electrons.
Proton 1 +1
The protons and neutrons are
found in the nucleus at the centre
of the atom.
The nucleus is very much smaller
Neutro
than the atom. 1 0
n
The electrons are arranged in
energy levels around the nucleus.
Electro Almost
–1
n zero
Ions
if an atom loses one or more
electrons, it becomes a positively charged ion
if an atom gains one or more electrons, it becomes a negatively charged
ion
Electronic structure (way in which electrons are arranged in an atom)
way in which electrons are arranged in an atom.
Link to the
Shell Maximum Electronic structure
periodic
feature
table
First 2
Number of shells Period number
Second 8
Number of electrons in
Third 8
outermost shell (valence Group number
electron)
Atomic
Numbers added together
number
Elements and
Compounds
An element is a substance that is made up
of one kind of atom only.
A compound contains two or more kinds of
atoms joined.
Atoms can be joined by bonds, which
makes a molecule.
Mixture- mix molecules/atoms of two different elements/compounds together
Element: 2 or more of same atom bonded. Ionic bonding is the
complete transfer
Compounds: 2 or more different atoms bonded together. of valence
electron(s) between
atoms
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