atoms, ions, molecules
TRANSCRIPT
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 1/38
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 2/38
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 3/38
Atoms, subatomic particles, symbolsIons
Molecules
Simple chemical formulae
Balancing Equations
E-learning
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 4/38
An element is a pure substance thatcannot be broken down into two or more
simpler substances by chemical means.
Matter is made up of tiny particles.There are 3 kinds of particles.
• Atoms
• Ions• Molecules
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 5/38
Matter is made up of tiny particles.
There are 3 kinds of particles.
• Atoms
• Molecules
• Ions+
+ + +
+ -
- - -
-
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 6/38
Cut a gold foil into half, andhalf, and half …
In the end what would you
be left with… ?
An Atom
Gold Element
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 7/38
Atoms: What is an atom?
An atom is the smallest particle of an element
that can take part in a chemical reaction.
An element contains identical atoms that are
of the same type and size
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 8/38
Atoms: Examples
A piece of aluminium foilconsists of only aluminiumatoms all of which have the
same size
A piece of copper containsatoms that are of a different
size from those in aluminium
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 9/38
Atoms: How small is it?
Diameter of about 0.1 nanometre( 1 x 10−10 metre )
It takes 1 000 000 000 000 000 or 1015
atomsto completely cover the head of a pin
The cross-section of hair can fit 1 000 000 or106 atoms
How small?
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 10/38
Atoms: Subatomic Particles
Atoms are further made up of three types of particles. They are called:
Nucleus
Proton
Neutron
Electrons
Electrons orbit around the nucleus in
a path known as electron shell.
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 11/38
Atoms: Charges of Subatomic Particles
Nucleus
Proton =
positively
charged
Neutron =neutral
Electrons =
negativelycharged
Electrons orbit around the nucleus in
a path known as electron shell.
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 12/38
Atoms: Subatomic Particles
Particle Actual mass
(kg)
Relative
mass
Relative
charge
Found in
Proton
1.67 x 10
-27 1
1+ Nucleus
Neutron 1.67 x 10-27 1 0 Nucleus
Electron 9.11 x 10-31 ≈ 0.0005 1- Shells
(orbitals)
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 13/38
Some Exercises
Particle Relative
mass
Relative
charge
Proton 1 1+
Neutron 1 0
Electron ≈ 0.0005 1-
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 14/38
Structure of an Atom
The nucleus consists of protons and neutrons.
The nucleus has a positive charge, due to the
positively charged protons.
The electrons have negative charges and they
orbit around the nucleus.
Neutrons as the
name suggests, is
neutral
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 15/38
Brilliance of the Periodic Table
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 16/38
Brilliance of the Periodic Table
Na23
11
Atomic Symbol
of Element
Mass No. or
Nucleon No.
Atomic No. orProton
Number
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 17/38
Brilliance of the Periodic Table
Hence from the periodic table, you can determine thenumber of protons and neutron. How about the number of
electrons?
In an atom,
the no. of electrons = no. of protons
Atomic (proton) number: is the number of protons in
an atom
Every element has a unique proton number. It does not
change.
Mass (nucleon) number: is the total number of
protons and neutrons in the nucleus.
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 18/38
Some Exercises
Element No. of protons No. of neutrons No. of electrons
8 8 8
6 6 6
4 5 4
56 81 56
18 22 18
16
8O
Ar 40
18
C 12
6
Ba
137
56
Be9
4
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 19/38
More Exercises: Don’t Complain
NucleusElectron
Base on the above diagram, state the number of
protons present in the nucleus?
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 20/38
Summary
Definition of an atom
Size of an atom
Sub-atomic particles and their properties
Symbol for the atom
Atomic number and mass number
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 21/38
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 22/38
What is an atom?
An atom is the smallest particle of an element that cantake part in a chemical reaction.
What are the three subatomic particles that make up
an atom?Protons, Neutrons and electrons
What particles are found in the nucleus of an atom?What electrical charge do they have?
Proton (positively charge)
Neutron (no charge)
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 23/38
What particles move around the nucleus? What electrical
charge do they have?Electrons. Negatively charged.
There is one kind of atom with no neutron. Which atom is it?
The hydrogen atom
What makes one kind of atom different from other kinds of atoms?
Each atom has a unique number of protons
What are the elements in the Periodic Table arranged inorder of?
They are arranged in order of proton number.
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 24/38
Electron Arrangement of Atoms
Nucleus
Proton
Neutron
Electrons
Electronic configuration and electronic structure
refers to the way the electrons are arranged in an atom.
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 25/38
Electron Arrangement of Atoms
Electrons are arranged in shells around the nucleus
Nucleus
Shell
Electrons
Electrons can be filled in theshell and there is a fixed
number of electrons that cango into each shell.
First shell: maximum of 2electrons.
Second shell: maximum of 8electrons.
Note: The order at which we
draw in the electrons isimportant, North, South, East,West
Third shell: maximum of 8electrons.
Note: The inner shell must be filled in FULLY before moving
on to the outer shell
El A f A
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 26/38
Electron Arrangement of Atoms
Na
Let’s take a look at an example of drawing an atom, Sodium
From the periodic table, Sodium, Na lookslike this
Therefore Sodium, Na has11 electrons
(1) We start by first
drawing the Symbol
of Sodium.
(2) Draw the 1st shell
(3) The 1st shell can fill
two electrons. Note
the order in which it is
drawn. NSEW
(4) Draw and fill on the 2nd shell with 8 electrons.
(5) Since Na has 11
electrons, we need to
draw a 3rd shell
Key:
represents
electrons of Na
Electron Arrangement of Atoms
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 27/38
Electron Arrangement of Atoms
S
Let’s do that again with Sulfur, S atom.
From the periodic table, Sulfur, S looks like this
Therefore Sulfur, S has 16electrons
(1) We start by first
drawing the Symbol
of Sulfur.
(2) Draw the 1st shell
(3) The 1st shell can fill
two electrons. Note
the order in which it is
drawn. NSEW
(4) Draw and fill on the 2nd shell with 8 electrons.
(5) Since S has 16
electrons, we need to
draw a 3rd shell
Key:
represents
electrons of S
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 28/38
Beautiful, NEAT drawings
When drawing an atom, using the CIRCLE stencil (buyfrom book shop) will really help achieve the above.
Key!
All atomic drawing MUST come with a Key! Else wewont know what your means
Electron representation.
We can use a few shapes to represent electrons.
(a) (b) (c)
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 29/38
Electron Configuration of Atoms
F
Electron configuration of atoms is the numerical representationof electrons found in the electron shell .
From the periodic table, fluorine has 9 electrons
Key:
represents electrons of F
Electronic configuration of Fluorine
2.7
This number
represents the numberof electrons in the first
shell
This number
represents the numberof electrons in the
second shell
The addition of these two numbers should give
the total number of electrons of fluorine
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 30/38
Some Exercises (my favorite part cos its not yours.. WAHAHAHA)
Draw the electronic structure and state the electronic
configuration of the first 20 elements.(Yes I say 20 and its not a typo)
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 31/38
Valence electron of Atoms
O
The electrons in the outermost shell is known as thevalence electron.
From the periodic table, Oxygen has 8 electrons
Key:
represents electrons of O
Electronic configuration of Oxygen: 2.6
Number of Valence
electron in Oxygen: 6
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 32/38
The true brilliance of the Periodic Table
Exercise: Your task is to find a pattern between what you have
learnt thus far and the periodic table. As a cool teacher, I’ll give
you a clue. Use the electronic configurations of the first 20
element to find a pattern between it and the periodic table
When you figure it out, you’ll truly feel brilliant
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 33/38
Recall: Charges of Subatomic Particles
Nucleus
Proton =
positively
charged
Neutron =neutral
Electrons =
negatively
charged
The negatively charged electrons are attracted tothe positively charged nucleus by electrostatic force.
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 34/38
Charge of an atom
Base on the charges of the sub-atomic particles,what do you think is the charge on an atom?
An atom has no charge (i.e. electrically neutral)This is because…..
In an atom,
the no. of electrons = no. of protons
The charges on the protons and the
electrons balance each other.
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 35/38
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 36/38
Isotopes
Isotopes are atoms of the same element having the samenumber of protons but different number of neutrons.
Example 1: Hydrogen has 3 isotopes
1
1 H
2
1 H
3
1 H
Protons 1 1 1
Neutrons 0 1 2
Electrons 1 1 1
1
1 H
2
1 H
3
1 H
Hydrogen Deuterium Tritium
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 37/38
Isotopes
Example 2: Carbon has 2 isotopes
Protons 6 6
Neutrons 6 8
Electrons 6 6
Carbon – 12 Carbon – 14
C 12
6
14
6
C
C 12
6
14
6C
8/3/2019 Atoms, Ions, Molecules
http://slidepdf.com/reader/full/atoms-ions-molecules 38/38