Post on 30-Apr-2020
The periodic table is organized like a big grid.
Each element is placed in a specific location because of
its atomic structure.
WHERE DO THE NAMES OF ELEMENTS COME FROM?
➤ In Latin…• Gold = Aurum (Au is chemical symbol)• Silver = Argentum (Ag is chemical symbol)• Lead = Plumbum (Pb is chemical symbol)
➤ Einsteinium = Es
ATOMIC MASS
➤ The average mass of 1 atom of the element➤ The sum of the number of protons and neutrons in the nucleus of an atom
➤ Note: Electrons are not part of the atomic mass, because they are too light to add mass to an atom
ATOMIC NUMBER
➤ Elements of the periodic table are arranged by atomic number.➤ The number of protons in the nucleus of an atom.➤ If you know the number of protons, you can identify the element since the atomic number is equal to the number of protons.
IMPORTANT FORMULASAtomic Mass = Neutrons + Protons
Number of Neutrons = Atomic Mass - Atomic Number
Number of Neutrons = Atomic Mass - Proton Number
IONS➤ When an element is missing or has an extra electron.➤ Does not affect the mass of an element.➤ Will give an element either a negative or a positive charge.
What is an ELEMENT?o A substance composed of a single kind of atom.
o Cannot be broken down into another substance by chemical or physical means.
What is a COMPOUND?o A substance in which two or more different elements are CHEMICALLY bonded together.
➤Homogenous Mixture: A mixture where all
particles are evenly distributed throughout. You cannot pick out one type of particle from a homogenous mixture.➤ Example: Air, Iced-Tea (if mixed properly)
➤Heterogenous Mixture: A mixture where
all particles are not evenly distributed throughout. Different samples of mixture are not identical to one another. You can pick out one type of particle from a heterogenous mixture.➤ Example: Cereal and milk, pizza, blood, vegetable soup
MOLECULES/PARTICLES➤ Composed of a cluster of atoms and can be broken down into those atoms during a chemical change.➤ Can be made up of more than one type of element.
PURE SUBSTANCES➤ A substance that contains only 1 kind of particle/molecule.➤ A material that has consistent properties and constant composition.
➤ Example: Water, Tin, Sulfur, Table Salt, Sugar, Baking Soda
EXAMPLESHydrogen gas (H2) is a molecule, but not a
compound because it is made of only one
element.
Water (H20) can be called a molecule or a
compound because it is made of hydrogen
(H) and oxygen (O) atoms.
Chemical Formulas are used to identify compounds using:
- Element Symbols - Numbers
The element symbols will never change from the periodic table (you can always use the periodic table to see which
symbol is for which element).
The numbers in chemical formulas are called subscripts. They tell you how many atoms of each element is in the compound. If there is no number as a subscript, there is ONE atom of this element.
For example:
COMPOUND ELEMENTS HOW MANY ATOMS?
Ag
F
1
2
Sr
Cl
1
2
F
Mo
O
2
1
2
Cd
Cl
1
2
C
H
N
O
P
3
8
1
5
1
Br
O
1
3
Al
F
Li
1
6
3
What would the following chemical formulas
be?
Even though they skip some squares in between, all of the rows read
left to right. When you look at the periodic table, each row is called
a period
All of the elements in a periodhave the same number of atomic
orbitals.
For example, every element in the top row (the first period)
has one orbital for its electrons.
The periodic table also has a special name for its vertical columns. Each column is called
a group or family
Those outer electrons are also called valence electrons. They are the electrons involved in
chemical bonds with other elements.
Every element in the first column (group one) has one electron in its
outer shell. Every element in the second column (group two) has two
electrons in the outer shell.
Hydrogen (H) and helium (He) are special elements. Hydrogen, in its neutral form,
does not have a neutron. There is only one electron and one proton.
Reactivity➤ All atoms want to be stable.
➤ Losing, sharing or gaining electrons is a way to become stable.
➤ When the outer shell is filled (in a Bohr diagram), elements are stable.
ReactivityThe number of
electrons indicates reactivity.
➤ If an element is missing one or two electrons in its valence shell (outermost shell in a Bohr diagram), it is considered reactive!
➤ Which Groups in the Periodic Table would have elements that are reactive?
FAMILIES: ALKALI METALS➤ First column (except Hydrogen)➤ Have one electron in their outermost level (1 valence electron)➤ Shiny, have consistency of clay, and are easily cut with a knife➤ The most reactive metals➤ React violently with water➤ Never found as free elements in nature, and are always bonded with another element
ALKALI METALS◆Most commonly
known Alkali metal:
–SODIUM
–When combined with Chlorine, makes Sodium Chloride…
–AKA Table Salt.
FAMILIES: ALKALINE EARTH METALS➤ Second column➤ They have 2 valence electrons➤ Solids➤ They are never found uncombined in nature➤ Not as reactive as Alkali Metals, they still bond easily due to their 2 valence electrons➤ Examples: Magnesium and Calcium
ALKALI EARTH METALS◆Magnesium
burns so actively in the air that it is
often used in flares.
◆Burns a brilliant, bright white.
FAMILIES: HALOGENS➤ Second last column➤ Can exist in solid, liquids or gases at room temperature depending on the element➤ Have 7 valence electrons which explains why they are the most active non-metals➤ Only need to gain 1 electron to fill their outermost energy level➤ They are never found free in nature
FAMILIES: CHALCOGENS➤ Third last column, Group 16➤ Solids and gases➤ Have 6 valence electrons➤ Most elements share electrons with Chalcogens when forming compounds➤ This group varies the most in properties➤ Oxygen is the most abundant element in the Earth’s crust. It is extremely active and combineswith almost all elements
CHALCOGENS◆OXYGEN: We need
it to breathe and survive.
◆POLONIUM: Used to clean photography equipment.
FAMILIES: NOBLE GASES➤ Inert Gases➤ Last column of periodic table➤ Colourless gases that are extremely un-reactive, because their outermost energy level is full➤ They do not readily combine with other elements to formcompounds (thus called inert)➤ Examples: Helium, neon
METALS◆ Constitute
more than 75% of all the elements.
◆ Concentrated on the left side and center of the table.
METALS◆Physical Properties of Metals:
–Shiny
–Generally a silver colour (except for gold and copper)
–Malleable
–Ductile
–Solid at room temperature (except Mercury)
–Conducts heat and electricity.
Examples of Metals
Chromium: Used in
making stainless
steel.
Barium: Used in
glassmaking
and in rat
poison
Scandium:
Used in high
intensity
lights. Thallium: Used in ant
killer and in treating
ringworm (in small,
controlled amounts)
NONMETALS◆ Constitute about 15% of the elements.
◆ Located on the far right side of the periodic table.
NONMETALS◆Physical Properties of Nonmetals:
– No lustre (shine)
– Brittle (not malleable or ductile)
– Non-conductors or insulators of heat
– Non-conductors or insulators of electricity (except graphite)
– Either solid or gas at room temperature (except bromine)
NonmetalsSulfur: Used in
making matches
and in
pyrotechnics
Neon: Used in light
signs and in lasers.
Fluorine: Used
in rocket fuel.
Radon: Naturally occurring
gas that can be a side
product of nuclear power
plants.
METALLOIDS◆Physical Properties of Metalloids:
–Have properties of both metals and nonmetals.
–All are solid at room temperature.
–Some have lustre (shine)
–Tend to behave like nonmetals (except in terms of electrical conductivity)
Metalloids
Boron: Used
in fighter
aircrafts and
in soaps.
Arsenic: Used in
the treatment of
cancer, but can be
poisonous in large
amounts.
Silicon: Used
in electronics
and automotive
parts.