Transcript Lesson 1 - Using the Periodic Table

Lesson 1 - Using the Periodic Table
Dimitri Mendelev knew that some elements were very
similar, and it made sense to him to group them together.
For example, he grouped together sodium, lithium and other
metals that reacted violently with water.
In 1886, the element Germanium was discovered. This
element had the exact properties of a missing element on
Mendeleev’s table.
Henry Mosley rearranged the elements to the table we have
now based on the atomic number of the elements.
Alkaline Earth Metals
Alkali Metals
Halogens
Nobel Gases
TRANSITIONAL
METALS
Period
Horizontal row of elements in the periodic table
They are numbered from 1 to 7.
The most reactive metals start on the left, as you move right
the metals become less reactive.
Group/Family
Vertical column of elements in the periodic table
They are numbered from 1 to 18
Elements in the same group have similar reactivity.
Element Symbol & Name
Element symbols are used to describe elements because they are the
same in every language and it will make communication easier.
An element symbol consists of 1 or 2 letters.
The first letter is capitalized, and if there is a second letter it is lowercase.
The rule about capitalization is very important. Ex. The symbol Co
stands for cobalt, while CO represents Carbon Monoxide (a compound
that contains both Carbon and Oxygen)
The symbol is sometimes an abbreviation of the elements English name,
other times it abbreviates the Latin name. Ex/ the symbol for Silicone is
Si where as the symbol for Silver is Ag because its Latin name is
Agentanium.
Some elements are named based on where they were discovered, like
californium which was discovered at the University of California.
Titanium is a strong yet light metal element. It is named for the Titans,
powerful gods of Greek mythology.
Atomic Number
The atomic number is typically found in the top left corner of each
element square.
It shows how many protons are in one atom of that element.
Atoms have a neutral charge, therefore the number of electrons
equals the number of protons.
As you move across the periodic table from left to right the atomic
number increases by one.
Ex/ Nickel’s atomic number is 28, therefore it has 28 protons and
28 electrons
Atomic Mass
Typically found under the elements name in each element
square.
Atomic mass is always expressed as a decimal, because each
element, except for Fluorine, can form isotopes, which are
atoms with different numbers of neutrons in them and
therefore different masses.
Atomic mass is the average mass of all an element’s different
isotopes.
Mass is measured in Atomic Mass Units (amu).
Hydrogen has an atomic mass of 1.01 amu and iron has an
atomic mass of 55.85 amu. This means that iron is 55 times
heavier than hydrogen atoms.
Mass Number
The mass number of an element is the atomic mass
rounded to a whole number.
It is the total number of protons and neutrons in an
atom.
Electrons are too small, therefore they have very little
effect on the total mass of the atom.
To determine the number of neutrons an element
has subtract the atomic number or protons from the
mass number (ROUNDED!)
MASS NUMBER – ATOMIC NUMBER = NEUTRONS
(OR PROTONS)
Isotopes
A form of an atom that has a different number of neutrons than
the common form of that atom.
Ex. The most common form of hydrogen has 1 proton and 1
electron but 0 neutrons. A small percentage of hydrogen atoms
have 1 proton, 1 electron, and1 neutron.
An even smaller percentage of hydrogen atoms have 1 proton, 1
electron and 2 neutrons.
The most common form of carbon contains 6 protons and 6
neutrons, therefore has a mass number of 12.
Carbon-14 is an isotope of carbon that has a mass number of 14.
Because it isn’t the most common form of carbon, its mass
number is indicated with “-14” at the end of the element name.
Carbon-14 is used for carbon dating.
Ion Charge
Ions are formed when atoms or groups of atoms
gain or lose electrons.
Ion charge is the electric charge that an atom takes
on when it loses or gains electrons.
Elements that gain electrons become negatively
charged, whereas elements that lose electrons
become positively charged.
Elements with atoms that form similar ions are
grouped together in the periodic table.
For example, elements in the first column on the
left side of the periodic table all form positive ions
of ion charge +1.
Element Element Atomic
Name Symbol Number
Atomic
Mass
Mass
Number
Ion
Charge
Hydrogen
1.01
1
+1
H
Bromine 81
Iron
Titanium46
1
Br
35
81
81
-1
35
56
+2, +3
26
0
35
46
55.85
Ti
22
46
46
+3, +4
22
Pb
82
207.21
207
+2, +4
82
82
235
+6, +4
92
92
+5, +4
23
23
U
92
235
Vanadium
V
23
50.94
Magnesium
1
26
Uranium –
235
Argon
1
Fe
Lead
Phosphorus
# of
# of
# of
Protons Electrons Neutrons
51
26
22
30
24
125
143
28
P
15
30.97
31
-3
15
15
16
Ar
18
39.95
40
n/a
18
18
22
Mg
12
24.31
24
+2
12
12
12
238.03
238
+6, +4
92
92
146
6
Uranium
U
92
Carbon
C
6
12.01
12
+4,-4
6
6
Helium
He
2
4.00
4
n/a
2
2
2
Metals, Non-Metals and Metalloids
Metals
Metals are found of the left side of the periodic table.
Physical Properties
– Most are shiny and silver/grey.
– Excellent conductors of heat and electricity.
– They are also malleable and ductile.
– Most metals are solid at room temperature. Mercury is a
metal that is liquid at room temperature.
Chemical Properties
– Some metals react explosively with water (Ex. Sodium
(Na))
– Others will not react even if mixed with strong acid (Ex.
Platinum (Pt))
Non – Metals
Only 17 of the known elements are classified by scientists as nonmetals.
These elements are not grouped because of their similarities but
because they don’t resemble metals.
Non-Metals are found of the right side of the periodic table.
Physical Properties
11 of the non-metals are gases at room temperature, 5 are solid, and 1
is liquid.
Solid non-metals do not conduct heat or electricity.
Solid non-metals are brittle and not malleable elements.
Solid non-metals have little or no metallic lustre.
Chemical Properties
Some non-metals are very reactive.
Sulfur is a yellow solid. It is a very reactive poisonous gas and will
burn in air. It will melt into a liquid with little heat.
Pure bromine is very reactive and toxic.
Metalloids
Have both metal and non-metal properties.
They are often used in electronics, such as
computers.
Physical Properties
Metalloids conduct electricity not very well, they
are called semi-conductors.
Silicone is the most common metalloid. It is
shiny and grey, but unlike a metal, it is brittle.
About 40% of the mass of any rock comes from
silicon. It is also a major component of glass.
Element Families
Alkali Metals
Group 1 elements
Similarities
Silver – grey in colour.
Like other metals, they are malleable and ductile; they
conduct heat and electricity.
Unlike other metals, they have low melting points and melt
below 181°C.
These are the Alkali metals
These metals react when exposed to water or air.
Differences
From top to bottom, density increases, and reactivity
decreases.
Alkaline-Earth Metals
Group 2 elements
Silvery – white in colour.
These elements also react when exposed to water
or air, however their reactivity is not as violent as
alkali metals.
They are harder and have a higher density than
sodium and potassium
Alkaline-Earth Metals have higher melting points
that alkali metals.
Halogens
Group 17 elements.
Similarities
Each has a noticeable but different colour.
They all have a low melting points.
They are the most reactive non-metals.
Differences
Moving from top to bottom, the colours of the
vapours grow in intensity.
Also, melting points increase.
Noble Gases
Group 18 elements
Similarities
All exist naturally colourless gases, but will glow
with bright colours if an electric charge is run
through them (Neon lights).
They are the most stable and unreactive
elements.
Differences
From top to bottom, the density increases.
Classification of Matter
Pure Substances
- Contain only one type of
particle
- can exist in three states of
matter: solid, liquid and gas
Compounds
- Examples:
water, salt,
sugar
Elements
- Examples:
iron, gold,
oxygen
All Matter
Homogeneous
Mixtures
(Solutions)
- appear to be one
substance
- particles of
different
substances are
intermingled
- examples:
vinegar, clear air
Mixtures
- contain two or more
substances
Heterogeneous
Mixtures (mechanical
Mixtures)
- two ore more parts
can be seen
- different kinds of
particles stay together
- examples: soil,
blood, concrete
Identify each mixture as homogeneous or
heterogeneous.
Dirt
Heterogeneous Mixture
Sterling silver bracelet
Homogeneous Mixture
Sample of pond water
Heterogeneous Mixture
Recycled paper
Heterogeneous Mixture
Read the descriptions below. In the space provided,
indicate whether each mixture is a mechanical mixture
(MM) or a solution (S)
• The different substances in this mixture can be
distinguished from each other with the unaided
eye or a magnifying glass MM
• The substances in this mixture cannot be
separated by filtering S
• When this mixture is left to stand undisturbed,
the substances do not separate by floating to
the top or settling to the bottom. S
• This mixture appears cloudy or opaque. You
cannot see through it clearly. MM
Combining Metals
Some metals, such as tin and gold, are too weak to be used
alone for some purposes. Therefore, to make a substance
stronger, some metals are often melted and mixed with other
melted metal elements.
The mixture is cooled to become a solid solution. A solution
of two or more metals is called an alloy.
Common alloys include a combination of gold and nickel or
manganese, this is often called white gold because it has a
lighter colour than pure gold.
White gold is often used in engagement rings and wedding
bands to give them strength and durability.
Alloys are used in magnets, sports equipment, vehicles and
many other household items.
Types of Compounds
Ionic Compounds
Properties
Ionic compounds have high melting points (they
are solid at room temperature).
When dissolved in water, they are good
conductors.
They all form crystals.
How they are formed:
Ionic compounds are pure substances formed as a
result of the attraction between ions of opposite
charges.
Metal atoms tend to lose electrons, therefore they
become positive ions. Whereas, non-metal atoms tend
to gain electrons, therefore they become negative ions.
Ex/ When sodium combines with chlorine, an electron
from the highest energy level of a sodium atom moves
to the outer level of the chlorine atoms. This cause the
atoms to become neutral.
Consider the Bohr Model for both Chlorine and Sodium:
Molecular Compounds
Composed of 2 non-metals.
May be solid, liquid or gas at room temperature.
Tend to be insulators or poor conductors of
electricity (because there is no charge associated
with their creation).
They have relatively low melting and boiling
points due to the weak forces between
molecules.
In a molecular compound, atoms join together
by sharing electrons in the highest energy level.
Consider the Bohr Diagrams for both Hydrogen and
Oxygen (to make water):
Diatomic Molecules
Molecules composed only of two atoms of
the same element are Diatomic Molecules.
Common diatomic molecules are Hydrogen,
Nitrogen, Oxygen, and the halogens
(Fluorine, Chlorine, Bromine, Iodine, and
Astatine)
Physical State of Compounds
Commonly a chemicals state at room
temperature will be indicated behind the
element compound as a subscript.
S – solid, l – liquid, g – gas, aq – aqueous
(dissolved in water)
Symbols
The symbol of each element that is contained in a compound will be
written in the chemical name of that compound
Ex/ NaCl
***Remember – there are 1 or 2 letters in each compound symbol
and the first letter is capitalized, the second is lowercase
Therefore the two symbols in NaCl are Na and Cl, which means that
Sodium and Chlorine are contained in NaCl
There are sometimes numbers behind a chemical symbol,
these numbers show how many atoms of each chemical
are in the compound
Ex/ H2O
2 Hydrogen and 1 Oxygen molecule
WATER
symbol for hydrogen
H2O
symbol for oxygen
each molecule contains two
atoms of hydrogen and one atom
of oxygen
CARBON DIOXIDE
symbol for carbon
CO2
no number, represents
one atom of carbon
symbol for oxygen
each molecule contains two
atoms of oxygen in each
molecule
CARBON MONOXIDE
symbol for carbon
CO
one atom of carbon
symbol for oxygen
one atom of oxygen
Compound
Element in compound
Molecular or Ionic
Number of Atoms in Each
Drawing of Compound
Element
CaO
CaCl2
Al2O3
Na2O
AlCl3
NaOH
Calcium; Oxygen
Ionic
Calcium;
Chlorine
Ionic
1 Calcium;
1 Oxygen
Ca
1 Calcium;
2 Chlorine
Cl
Aluminum
Oxygen
Ionic
2 Aluminum
3 Oxygen
Sodium
Oxygen
Ionic
2 Sodium
1 Oxygen
Ionic
1 Aluminum
3 Chlorine
Aluminum
Chlorine
Sodium
Oxygen
Hydrogen
Ionic &
Covalent
1 Sodium
1 Oxygen
1 Hydrogen
O
Cl
Ca
Al
O
O
Na
O
Na
Cl
Al
Al
Cl
Na
O H
Cl
O
Chemical Formula
Matter cannot be created or destroyed.
In chemical equations, both sides must contain
the same number of atoms of each element.
Large numbers in front of a compound indicate
how many molecules of the compound are used
in the chemical equation.
Ex/ 2CH3OH + 3O2 -2CO2 + 4 H2O
In CH3OH, there is 1
carbon, 4 Hydrogen, and
1 Oxygen and in O2 there
are 2 oxygen.
The formula uses 2 of
CH3OH molecules and 3
O2, therefore on the left
side of the formula…
2 – Carbon
8 – Hydrogen
8 – Oxygen
On the left side of the
equation, there are 2
molecules of CO2 and 4
molecules of H2O.
Therefore there are:
2 – Carbon
8 – Hydrogen
8 – Oxygen
Ex/ Mg + S  MgS
24.3g 32.1g
56.4g