Structure and bonding
Title
• Atomic structure
Aim
• to draw and label the sub atomic particles
of an atom.
This dotted line is called The Staircase – it divides
metals (left) from non-metals (right)
12
A column is called a
345678
Group. There are 8
A row is called a PERIOD
VIDEO
Quick quiz
1. What is found in the periodic table?
2. What are the rows called?
3. What are the columns called?
4. What element is found in:
a) Group 8 period 2- Ne (neon)
b) Group 6 period 2- O (oxygen)
c) Group 1 period 4- Na (sodium)
This dotted line is called The Staircase – it divides
metals (left) from non-metals (right)
Atoms
ELEMENTS are made up of ATOMs.
ATOMs are all made up of protons, neutrons and
electrons.
The Nucleus – this
contains neutrons
and protons
Electrons – these
orbit around the nucleus
Different elements have different
types of atoms.
What the difference?
Protons =2
Protons =4
Helium
Beryllium
Atomic Number
• The atoms of same elements always
contains the same number of protons.
E.g.
– Hydrogen atoms always contain 1 proton
– Carbon atoms always contain 6 protons
– Magnesium atoms always contain 12 protons
• The number of protons is the atomic
number.
• It is the smaller of two number
12
C
6
There are 3 parts of an atom
Type of sub atomic
particle
Relative charge
Proton
+1 (positive)
Neutron
0 (neutral)
Electron
-1 (negative)
1/2000 of the size of a
proton
Activity
How Many Protons?
• Here is some data about elements
taken from the Periodic Table.
• What is the atomic number of the
elements?
23
56
119
19
27
Na
Fe
Sn
F
Al
11
26
50
9
13
11
26
50
9
13
What element is it?
•
•
•
•
•
•
•
Atomic number.
12-Magnesium (Mg)
8- Oxygen (O)
6- Carbon (C)
20-Calcium (Ca)
3- Lithium (Li)
2- Helium (He)
Atomic number
• Atomic number = number of
protons.
• Atomic mass is the number
of protons and neutrons
added together
12
C
6
Atoms
• In atoms
number of protons
= number of electrons
So if the atomic number is 8 it will have,
8 protons
and
8 electrons
Why do atoms have
charge?
NO
Activity
• Complete as a class
Atom
Helium
Nitrogen
Oxygen
Magnesium
Sodium
Symbol
Protons Electrons
+
-
Charge
What is an isotope?
• Different forms of the same element.
• Same atomic number BUT a different
number of neutrons and thus a different
mass number.
•99.76% of oxygen atoms have
this configuration.
16
• Eg
8
O
•0.04% have the mass number
of 17
•0.20% have the mass number
of 18
*Drawing Atoms*
Aim:
• To accurate diagrams of the electron
structure of the first 20 elements.
How Are Electrons Arranged?
• Electrons are not evenly spread.
• The exist in layers known as shells.
• The arrangement of electrons in these shells is often
called the electron configuration.
1st Shell
2nd Shell
3rd Shell
4th Shell
Electron configuration
• Shows how electrons are organised at an
atomic level.
Shell
1st
2nd
Max
numbers of
electrons
2
8
3rd 4th
8
2
Which Shells Do Electrons go into?
• Opposites attract.
• Protons are positive (+) and electrons are
negative (–) charged.
• Electrons will occupy the shells nearest the
nucleus unless these shells are already full.
1st Shell: Fills this first
2nd Shell: Fill this next
3rd Shell: And so on
The Electrons in Carbon
The Electrons in Silicon
The Electrons in Neon
Ions and Electron Structures
1. Ions are atoms that have either extra
electrons added or electrons removed. e.g.
Atoms
Protons
Electrons
Lose 1 electron
1+ ion
Gain 1 electron
Protons
Electrons
So in ions the
number of
electrons no
longer equals the
number
of protons
1- ion
Protons
Electrons
The Electrons in a Sodium Ion
In the sodium atom
Atomic number = number of protons
Number of electrons = 11
Na
23
= 11 Na
11
Na+
Bye!
Electron
lost
Electron arrangement:
2.8.1 (Incomplete Shell)
Electron arrangement:
2.8 (Full Shells)
The Electrons in a Magnesium Ion
In the magnesium atom
Atomic number = number of protons
Number of electrons = 12
24
= 12 Mg
12
Bye!
Mg2+
Mg
Bye!
Electron arrangement =
2.8.2 (Incomplete shell)
2 electrons
lost
Electron arrangement
2.8 (Full Shells)
Activity
The Lithium Ion
•How many electrons?
3
•How many electrons in the first shell?
2
•How many electrons in the second shell?
1
What electron arrangement?
7
Li
3
2.1
1st Shell = 2: full
2nd Shell = 1: not full
How many electrons to lose?
1
Li
Li+
New electron arrangement?
Include a diagram
2.(0)
Bye!
Activity
The Boron Ion
•How many electrons?
5
•How many electrons in the first shell?
2
•How many electrons in the second shell?
3
What electron arrangement?
11
B
5
2.3
1st Shell = 2: full
2nd Shell = 3: not full
How many electrons to lose?
New electron arrangement?
Bye!
Bye!
3
2.(0)
BB3+
Bye!
Open to valence table 5.1
• Draw a before and after using a Bohr diagram
showing the following atoms becoming ions.
•
•
•
•
•
•
Sodium
Oxygen
Chlorine
Calcium
Nitrogen
Aluminium
Ionic Compounds
• Once an ion has been created it will
attract ions of the opposite charge they
form ionic compounds.
• For example magnesium + oxide =
magnesium oxide
• To write this as a chemical formula you
need to take into account the ions
charges (valencies)
Magnesium has a positive charge of 2
while oxide has a negative charge of 2.
Ionic
Formulas
Step 1 - write the name and symbols (the positive goes first)
Magnesium
Oxide
2+
2Mg
O
Write the valencies above the symbols
Step 2 - crisscross the valencies to get correct subscripts and leave out
the + & - signs
Magnesium
Oxide
2+
2Mg2
O2
Step 3 - write the correct formula with subscripts
Mg2O2 = MgO
(you can simplify this to MgO as each has 2 they cancel each other out)
Ionic formulas
• What happens when you try the following
• Potassium + oxide
•
•
•
•
Your new formula looks like this
potassium
oxide
1+
2K2
O1
• K2O
• When the charge is one only you can leave this
out
Ionic Formulas
•
Try these in your book (write ALL STEPS)
1. Calcium + oxide
2. Barium + oxide
3. Silver + chloride
4. Sodium + bromide
5. Lead + permanganate
•
Ionic
formulas
When they get more complex-
• Zinc
• 2+
• Zn
+
nitrate
1(NO3)
• Zn(NO3)2
•
•
•
•
Potassium + sulfate
1+
2K
(SO4)
K2SO4
Creating an ionic compound
• Aim: to make the ionic compound
Magnesium oxide and explain its bonding.
• What you know about Magnesium and
Oxygen. Colour, solid liquid or gas,
electron structure. Use pictures
Equipment & Safety
Equipment
• Goggles
• 2cm strip of Mg
• Heat proof mat
• Tongs
• Bunsen burner
Safety
• While heating Mg DO
NOT look directly at it.
• Ensure all heated
material stays on heat
proof mat
• Ties in
Observations
1. What did you
see hear and
smell?
2. What was the
product
formed?
3. What did it
look like?
Explaining observations
1. Why did you see or hear
something?
2. How can you explain why
magnesium and oxygen have
combined?
3. Use the electron configuration.
4. How many atoms form the
compound?
5. Does the properties change of
Mg and O?
6. Why does this happen?
7. Write and equation to show
this chemical reaction.
Negative Ions.
•
These are ions formed by the atom gaining one
or more electrons.
Gain 1 e
•
They are called anions. This is because during
It is nearly
Ions usually
electrolysis
they
move
towards
the
anode.
always
have
non-metal
OUTER
The
charge
number of
atoms
that on the ions is equal to theelectron
gain
electrons
that the atom has gained.shells that
Gain 3 eelectrons
3are either
completely
In equations the charge is usually shown
above
2- or
and to the right of the symbol. (E.g.. Ofull
). else
empty
Gain 2 e
•
•
-
2-
The Electrons in a Sulphide Ion.
In the sulphur atom
Atomic number = number of protons
Number of electrons = 16
32
= 16
S2-
S
2 electrons
gained
Electron arrangement:
2.8.6 (incomplete shell)
Electron arrangement
2.8.8 (Full shells)
S
16
The Electrons in a Fluoride Ion.
In the fluorine atom
Atomic number = number of protons
Number of electrons = 9
19
=9
F
F2-
F
1 electron
gained
Electron arrangement:
2.8.7 (incomplete shell)
Electron arrangement
2.8.8 (Full shells)
9
Activity
The Oxide Ion
8
•How many electrons?
•How many electrons in the first shell?
2
•How many electrons in the second shell?
6
What electron arrangement?
16
O
8
2.6
1st Shell = 2: full
2nd Shell = 6: not full
How many electrons to gain?
2
OO2-
New electron arrangement?
2.8
Drag the words at the top to their correct
places in the sentences.
Word check
1. Which of the following is not a subatomic particle?
A.
B.
C.
D.
Proton.
Isotope.
Neutron.
Electron.
2. The element Cobalt has a relative atomic
mass of 59 and an atomic number of 27.
Which of these is a true statement about
each neutral cobalt atom?
A.
B.
C.
D.
It contains 59 neutrons.
It contains 27 electrons.
It contains 32 protons.
It contains equal numbers of neutrons and
electrons.
3. The Periodic Table displays iron as shown
below. This indicates that Fe atoms:
56
A.
B.
C.
D.
Fe
contain 56 neutrons.
26
contain 30 electrons.
contain 26 protons.
contains more protons than neutrons.
4. Bromine consists of a mixture of two
isotopes: Bromine-79 and Bromine-81
• Which of the following is true:
80
Br
A.
B.
C.
D.
35
Both isotopes contain 35 protons.
Bromine 79 contains 46 neutrons.
Bromine 81 contains 44 neutrons.
Bromine-81 is more reactive than bromine79.