Download Additional Topic 1 Atomic structure class booklet with syllabus and

ATOMIC STRUCTURE
What makes atoms of different
different from each other?
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CHEM - ADDITIONAL BOOKLET 1
1
elements
ATOMIC STRUCTURE
You should:
Tick
Know that the relative masses of protons, neutrons
and electrons and their relative electric charges are
shown:
Proton : mass 1 : charge +1
Neutron : mass 1 : charge 0
Electron : mass negligible : charge -1
Understand that the atom as a whole has no electrical
charge because the number of electrons in the orbits
(shells) is equal to the number of protons in the
nucleus.
Know that all atoms of a particular element have the
same number of protons and atoms of different
elements have different numbers of protons.
Understand the terms atomic number and mass number
Use data given in the form
23
Na
11
to give the number of protons, neutrons and electrons
present in the atom.
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SUMMARY SHEETS
The atom at G.C.S.E
This is a three dimensional depiction of the atom
CARBON
A two dimensional depiction of an atom of CARBON
When we draw atoms at G.C.S.E level we draw them as two
dimensional pictures.
From the above diagram you can see that at the centre of the
atom there are tiny particles called
PROTONS.
 PROTONS are POSITIVE and have a mass of 1 ATOMIC
MASS UNIT (a.m.u).
 PROTONS are given the symbol p+
 The NUMBER of PROTONS in the NUCLEUS of an
atom give that atom its IDENTITY.
 The NUMBER of PROTONS in the NUCLEUS is given by
the ATOMIC NUMBER. The atomic number for each
element can be found in the PERIODIC TABLE.
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ELECTRONS
 ELECTRONS are NEGATIVE and are given the symbol e-.
 Electrons are so small; we say that their mass is
NEGLIGABLE.
 The NUMBER of electrons is also given by the ATOMIC
NUMBER.
 Electrons DO NOT give atoms their identity. The number
of electrons can CHANGE so that ATOMS become IONS.
 In a NEUTRAL ATOM the NUMBER OF ELECTRONS is
always the SAME as the NUMBER OF PROTONS.
 Electrons orbit the nucleus of an atom in shells
(sometimes known as orbits or energy levels).
Putting electrons into their shells
There are many shells around the nucleus of an atom. The
inside shell can hold TWO electrons. The next three shells
hold EIGHT electrons. Electrons fill shells from the inside out.
A new shell cannot be started until its inner shell is FULL.
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NEUTRONS
 Neutrons have a mass of 1 ATOMIC MASS UNIT a.m.u.
The same mass as the protons.
 Neutrons have NO OVERALL CHARGE they are said to be
NEUTRAL.
 Neutrons exist alongside protons in the NUCLEUS of an
atom.
 The number of neutrons can be found by taking the
ATOMIC NUMBER away from the MASS NUMBER.
 The MASS NUMBER is the mass of an atom which is the
same as the TOTAL number of protons AND neutrons as
they all weigh 1 a.m.u.
This information for fluorine tells us
the mass and atomic number for one of its atoms.
ELEMENTS
Atoms in a particular element are identical as they all contain
the same number of PROTONS. For example carbon is carbon
because its atoms contain 6 protons. If the atoms contained 7
protons the element would be nitrogen. It’s the protons not
the neutrons or electrons that tell us what element an atom is
part of.
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VALENCY
Many atoms react with others in order to ensure their outer
shells become full. This will make the atom more stable.
Atoms can achieve full outer shells by LOSING, GAINING or
SHARING electrons. The NUMBER of electrons lost, gained
or shared is called the VALENCY.
END OF SUMMARY SHEETS
Key skill communication
KEY WORDS
Read the summary sheets above and write down as much
information as you can about the following key words. Use
examples and diagrams where possible.
Word/phrase
Information
Atom
Use sodium as an example. Draw an
atom of sodium with its protons,
neutrons and electrons.
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Atomic number
Again, use sodium as an example.
Explain what information the atomic
number for sodium gives us.
Mass number
Sodium again!
Proton
Give general information about a proton
here. For example, where it is found,
what its mass is, what its charge is.
Explain how to use atomic numbers to
find out the number of protons.
Neutron
Give general information about a
neutron here. For example, where it is
found, what its mass is, what its charge
is. Explain how to use mass and atomic
numbers to find out the number of
neutrons.
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Electron
Give general information about an
electron here. For example, where it is
found, what its mass is, what its charge
is. Explain how to use atomic numbers
to find out the number of electrons.
Electronic Structure
Use sodium or any other element here to
talk about electronic structure which is
the way in which electrons are arranged
in their shells.
Valency
Write out the electronic structures for
sodium, magnesium, oxygen , chlorine
and neon and work out what their
valencies are.
The valency is the
number of electrons they each need to
lose, gain or share to gain a full outer
shell. If they already have a full outer
shell then their valency is zero.
NOW FILL IN THE FOLLOWING TABLE. Draw the electrons
as crosses. Draw the nucleus as a black spot but label the
correct number of protons and neutrons that would be within
it. Look up the periodic table for the atomic/mass numbers!
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symbol
At
Mass
n.o
n.o
H
1
He
2
Li
Electron
arrangement
Valency
of atom
1
1
7
Be
B
9
Picture of atom
C
6
N
7
O
F
9
Ne
Na
0
11
2:8:1
1
10
Mg
Al
13
Si
P
S
15
16
31
2:8:6
2
11
Cl
Ar
K
Ca
20
12
Key Words
Atom
the smallest part of a substance that cannot
be split into anything simpler.
Element
an element is made up of atoms that are all
identical as they each contain the same
number of protons.
Protons
positive sub-atomic particles that exist in the
nucleus of an atom.
Neutrons
neutral sub-atomic particles that exist in the
nucleus of an atom.
Electrons
negative sub-atomic particles that exist in
shells/energy levels that surround the nucleus
of an atom.
Mass n.o
the mass of a single atom which is due to the
total number of protons and neutrons it
contains.
Atomic n.o
the total number of protons in an atom. This
in turn is the same as the number of electrons
in a neutral atom (very often electrons are
lost or gained forming ions)
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