Transcript Matter Review

STRUCTURES & BONDING
Title
31/03/2016
MATTER
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MATTER is anything
that has mass and
takes up space.
STRUCTURES & BONDING
ATOMS
31/03/2016
“WHAT IS MATTER MADE FROM?”
A question which has been asked from the
ancient Greeks up to 19th century.
In 530 B.C., Democritus, a Greek
philosopher proposed that any matter could
be halved continuously until small indivisible
units could be reached.
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STRUCTURES & BONDING
ATOMS
31/03/2016
“WHAT IS MATTER MADE FROM?”
The ideas proposed by the Greeks were
generally unaccepted until in 1808, John
Dalton (a teacher!) proposed the modern
ATOMIC THEORY.
From his experiments he found that only
elements combined to form compounds. He
soon realised that elements were made up of
tiny indivisible spheres he called ATOMS.
ATOM
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STRUCTURES & BONDING
ATOMS
31/03/2016
Atoms are the building blocks of matter.
They are so small you cannot see them with
normal microscopes
Try cutting a strip of paper as small as you
can….
An atom would be another 40 cuts from the
smallest possible cut…at least!
ATOM
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STRUCTURES & BONDING
ELEMENTS
31/03/2016
“WHAT IS AN ELEMENT?”
An element is a substance which is only made
up of one type of atom.
Example, Carbon is made up of Carbon atoms.
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STRUCTURES & BONDING
STRUCTURE OF THE ATOM
31/03/2016
All matter is made up of atoms, but….
“WHAT ARE ATOMS MADE FROM?”
Atoms are made up of even smaller subatomic particles
called:
ELECTRONS
PROTONS
+
NEUTRONS
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STRUCTURES & BONDING
STRUCTURE OF THE ATOM
In the middle
of an atom,
the
NUCLEUS
can be found.
-
-
-
-
+
+
+ +++
+ +
Nucleus
ATOM
++ ++
+
- In nucleus,
PROTONS
and
NEUTRONS
can be found.
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-
-
-
Orbiting the
nucleus in
SHELLS,
ELECTRONS
can be found.
- -
-
-
NOT TO
SCALE!.
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STRUCTURES & BONDING
STRUCTURE OF THE ATOM
31/03/2016
The gap between electron shells and nucleus is very large on
a subatomic scale.
If an atom was the
size of a stadium…
…the nucleus
would be the size
of a pea on the
centre spot!!
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STRUCTURES & BONDING
THE SUBATOMIC PARTICLES
31/03/2016
Each subatomic particle has a MASS and a CHARGE.
ATOMIC PARTICLE
PROTON
+
NEUTRON
ELECTRON
-
RELATIVE MASS
RELATIVE CHARGE
1 Unit
+1
1 Unit
0
1/1840 (NOTHING!)
-1
(Masses and Charges are RELATIVE which means in
comparison to each other e.g. 1840 electrons will weigh the
same as 1 proton.)
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STRUCTURES & BONDING
CHARGES
31/03/2016
In an atom, the number of electrons is equal to the number
of protons.
This means that since there is a balance between the
number of positive and negative subatomic particles there is
NO OVERALL CHARGE. An atom must be electrically
neutral
+
+
BORON
+
ATOM
+
+
5 Electrons
5 Protons
No Charge
(5 Negatives)
(5 Positives)
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The structure of the atom
MASS NUMBER (Atomic Mass) =
number of protons + number of
neutrons
Atomic SYMBOL
Atomic NUMBER = number of
protons = number of electrons
STRUCTURES & BONDING
COMPOUNDS
31/03/2016
“WHAT IS A COMPOUND?”
A compound is a substance which is only made
up of two or more elements chemically bonded.
Example, Sodium Chloride is made up of
Sodium and Chlorine Atoms.
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Bohr-Rutherford Diagram
• 1. Calculate the number of protons and
neutrons.
• 2. Write the number of p+ and n0 in the nucleus
with a circle around them.
• 3. Draw the number of shells (circles) the atom
has – the period number tells you the number of
shells.
• 4. Calculate the number of electrons the atom
(same as the number of protons) or ion) has.
• 5. Place in the electrons into the shells. Shell1 –
2 e-, Shell 2 onwards gets 8.
Periodic Table
The periodic table is an arrangement of
the elements according to:
• The number of protons, neutrons, and
electrons
• Physical Properties - The way they look
• Chemical Properties - The way they act
Periodic Table
• 80% of the elements in the periodic table
are metals
• A smaller group consists of non-metals
• Separating the two are a set of elements
called metalloids.
The Periodic Table
 Shows the mass number and atomic number
 Gives the symbol of the element
mass number
23 Na
atomic number
11
Groups of Elements
 Vertical (up and down) columns on the
periodic table
 Indicates the number of electrons on the
outer most shell called valence electrons.
Periods on the Periodic Table
 The different rows of elements in the periodic table
are called periods.
 Numbered 1-7
 The period number of an element indicates the
number of orbitals or shells the element
has.
Periods on the Periodic Table
1
2
3
4
5
6
Using The Periodic Table
• In your notes, use your periodic tables to determine the
following for the elements at the bottom.
– The number of protons
– The number of neutrons
– The number of shells
– The number of electrons on the outer most shell
(valence electrons)
– Draw the atoms for each
Calcium (Ca), Magnesium (Mg), Chlorine
(Cl)
Important Terms
• Isotopes: atoms of the same element that
have a different number of neutrons.
• Atomic mass is the average mass of all
isotopes of a particular element
• Family is a group of elements with similar
properties arranged together in columns.
• Alloys are a mixture of two or more
metals.
The Periodic Table
Alkali
metals
Li
Be
Na
Mg
K
Ca
Halogens
These
elements
H
are metals
Fe
Ni
He
Cu
Zn
Ag
Pt
Noble
gases
Au
This line divides
metals from nonmetals
B
C
N
O
F
Ne
Al
Si
P
S
Cl
Ar
Br
Kr
I
Xe
Hg
These elements are
non-metals
Properties of Metals
• Most are solid at room temperature
• Most have a shiny appearance (lustrous)
• Their shape can be changed (malleable)
• Can be stretched and drawn into thin wires (ductile)
• Most conduct electricity and heat well
• Usually have high densities (ie. Sink in water)
Properties of Non-Metals
• Poor conductors of heat and electricity or are
insulators (don’t conduct at all).
• Low melting and boiling points (usually liquids
or gases at room temperature).
• Brittle - if a solid.
• Do not possess metallic luster (so dull)
Metalloids
• Behave mostly like non-metals
• But do have some metallic properties,
most importantly they can conduct
electricity.
Noble Gases (or inert gases)
• Group of elements that rarely react and
are stable.
Families of Importance
1. Group VIII – The Noble Gases
•
All are colourless gases
•
Occur naturally in the atmosphere
•
Very stable
•
Helium is safe and light, but the gases get
heavier and more dense the further you go down
the group.
Families of Importance
2. Group VII – The Halogens
•
•
•
•
•
Form ions with a charge -1
Found in nature as salts
Have coloured and poisonous vapours
Form diatomic molecules
As you move down the group, the atoms get
bigger and less reactive
Families of Importance
3. Group I – Alkali metals
•
•
•
•
•
Form +1 ions
Extremely reactive
Found in nature only as mineral salts
Have typical metallic properties
All alkali metals react violently with water,
producing an basic solution and hydrogen gas.
Families of Importance
4. Group II – The Alkaline Earths
•
Act in a similar but less reactive way as the
Group I elements