Atoms, Elements and the Periodic Table

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General

- Way of listing elements

- Listed by structure of atoms

- Includes how many protons as well as electrons on outer shell

-Listed in order of atomic number which is how many protons in nucleus

- First proposed by Russian chemist Dmitri Mendeleev in 1869

Why is it Called the Periodic Table?

- "Periodic" as all elements are lined up in cycles or periods

- From right to left, elements lined up in rows based on atomic number

- Lined up like this as elements in the same columns have similar properties.

- Each horizontal row is a period

- 7 or 8 total periods

- Left most element has 1 electron in outer shell

- Right most element has a full shell

Groups

- Groups are the columns

- 18 groups that have different properties

- The grouping helps chemists when working with elements

- Lining up helps understand how certain elements may react in certain situations

Element Abbreviations

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Elements

Atoms

- Millions of different substances (things).

- All substances made of atoms.

- Atoms are pictured as spheres.

- Size of atom determines what the element is.

- Only 118 different types of atoms or elements.

- Elements get combined to form different substances. e.g. 1 oxygen atom+ 2 hydrogen atoms = one particle of water which is a compound.

- Compound= multiple different elements combined together.

First 20 Elements Of Periodic Table

H= Hydrogen

He= Helium

Li= Lithium

Be= Beryllium

B= Boron

C= Carbon

N= Nitrogen

O= Oxygen

F= Fluorine

Ne= Neon

Na= Sodium

Mg= Magnesium

Al= Aluminium

Si= Silicon

P= Phosphorous

S= Sulphur

Cl= Chlorine

Ar= Argon

K= Potassium

Ca= Calcium

Elements

- Elements are the simplest substances that can not be split in a chemical reaction.

- An element is a substance that has only one type of atom.

- Elements can react with other elements to form a compound substance.

- Elements are either metals, non metals or metalloids.

- Elements are the simplest substances in the universe.

- Can be represented by symbols.

- Periodic Table contains all the known elements.

- First PT had groups of 3 elements that were similar. Called triads.

- More elements came along so triads were scrapped.

Compounds

A compound is a substance made from two or more elements

that have reacted chemically with each other.

Mixture

A mixture contains two or more substancesthat have not reacted chemically with each other.

A mixture is made of little bits of each substance mixed together.

A mixture can be separated by physical methods,

a compound can not.

Dalton's Atomic Model / Physical Properties

Atomic Theory/ Model states:

- All matter made up of tiny particles called atoms.

- Atoms in element are identical but each element had own type of atom.

- Atoms are indestructible and can't be created or destroyed.

- In compounds, each atom of element is always joined to a fixed number of other elements.

- In chemical reactions, atoms rearrange to make new substances.

- He thought particles had different shapes and sizes

Physical Properties

- All atoms in element are identical but each element has own type of atom.

- Differences in atoms gives elements its own properties.

- Properties of substance on its own are physical properties.

- Physical changes only involved in one substance

- Easy to reverse.

Examples of Physical Properties

- Colour

- Melting point

- Boiling point

- Density

- Strength

- Flexibility

- Conduction of heat

- Conduction of electricity

Symbols

- To show different atoms.

- First letter capital

- All countries use same symbol so all scientists can communicate.

- International Union of Pure and Applied Chemistry (IUPAC) set up all symbols.

Physical Change- A change where no new substance is formed e.g. changes of state.

Physical Properties and Change or Reaction

- Physical property is an adjective to do with how the materials react with energy.

Examples

- Shiny or dull (reacting with light energy)

- High or low melting point or boiling points (reacting with heat/ thermal energy)

- High or low heat conductivity (reacting with thermal energy)

- High or low electrical conductivity (reacting with electrical energy)

- Dense or not so dense (reacting with gravitational potential energy)

- Bendy of stiff (reacting with kinetic energy)

Change or Reaction

- Physical change is a change of state of matter. NO NEW SUBSTANCE IS FORMED!!!

Examples

- Freezing (when a liquid changes to a solid)

- Melting (when a solid changes to a liquid)

- Boiling/ evaporating (when a liquid changes to a gas)

- Condensing (when a gas changes to a liquid)

Chemical Properties

- New substance formed in chemical reaction.

- Hard to reverse chemical change.

- Chemical properties of substances describe how it reacts with other substances. Example: Flammability and reaction with acids.

- Mass of products of reaction will be same as mass of reactants.

- Since atoms can't be created or destroyed, no change in number of atoms so no change in overall mass.

- In compound, all atoms of one element are joined to fixed number of other atoms.

Chemical Formulae

- Ratio of elements in compound is shown in chemical formulae

Examples

- Magnesium oxide- MgO

- Hydrogen oxide (water)- H20

- Nitrogen- N2

- Carbon Dioxide- CO2

- Carbon Hydroxide (methane)- CH4

Chemical Change or Reaction

- a chemical property describes how the substance reacts in chemical reaction

Examples

chemical properties of group 1 alkali metals can:

- be very reactive (a substance that reacts with many other substances or reacts very easilly)

- form a metal hydroxide and hydrogen when reacting with water

- reacts easily with oxygen to form a metal oxide

chemical properties of group 0 noble gases are:

- very unreactive (they are inert)

Change or Reaction

- chemical change/reaction occurs when A NEW SUBSTANCE IS FORMED!!!

e.g., magnesium + oxygen produces magnesium oxide

this is a chemical reaction because a new substance is produced

e.g. carbon dioxide + water produces sugar (glucose) + oxygen

this is photosynthesis - new chemicals are made - old bonds between the atom were broken and new bonds were made.

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Periodic Table

- On Periodic Table, elements represented by symbols, eg., Ca = Calcium

- Periodic Table developed by numerous scientist building upon each others work.

- Mendeleev created the periodic table that we know today.

- Group is a vertical column in the PT.

- Period is a horizontal row on the PT.

- Periodic Table contains all the known elements.

- First PT had groups of 3 elements that were similar. Called triads.

- More elements came along so triads were scrapped.

Mendeleev's Table

- 1869: Mendeleev published his periodic table.

- Elements in order on increasing masses of atoms.

- Groups with similar chemical properties.

- Made sure all elements fit into groups with similar properties as other elements by changing order leaving gaps for undiscovered elements.

- Elements with similar properties in vertical groups.

- He was not always correct. When argon was discovered, Mendeleev thought it did not exist as it did not fit into his table.

- Joined the group discovered as the noble gasses with are very unreactive.

- Noble gasses are:

helium

neon

argon

krypton

xenon

- Lithium, sodium and potassium react with water to produce hydrogen+ a solution of the metals hydroxide (lithium+water produces hydrogen + lithium hydroxide)

- Chlorine, bromine and iodine react with most metals to form a solid compound (iron+chlorine produces iron chloride)

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Investigating Thermal Conductivity

To see if a substance conducts heat, we conduct and experiment where we see which element are more conductive. We attach drawing pins to a heat star and we attach different metals to it using vaseline and push pin. The heat star is then placed over the bunsen burner. When the vaseline melts, the push pin will fall off. Hence, we can conclude that first vaseline to melt are next to the mental which is the best heat conductor.

Copper was the best thermal conductor.

How Conduction Works

The heat starts at a group of particles which makes them vibrate even faster.

They collide with the rest of the particles until the temperature is the same all around.

Investigating Electrical Conductivity

Metals have the following properties:

- Shiny

- Bendy, if pure

- Good conductors of heat

- Good conductors of electricity

- Sonorous sound when hit

We can test whether substances can conduct electricity by setting up a circuit containing a battery, wires, bulb, all connected by wires.

The substance being tested is inserted into the circuit using crocodile clips. The substances tested were cooper, aluminium, iron, glass, wood and carbon.

If the bulb lit up, the substance is a good electrical conductor as the electricity is able to flow through the circuit to light the bulb.

All the metals conduct electricity. Carbon which is non- metal, also conducts electricity.

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Metal Properties

Properties of metals:

-flexible

-shiny

-good conductors of heat

-strong

-good conductors of electricity

these properties make metal useful in many way, e.g., building frames, water pipes, electrical circuits

- Iron can be used in building frames as it is strong and cheap.

- Copper can be used for water pipes as it is unreactive, malleable and non- poisonous.

- Copper can be used in electrical circuits as it is a good conductor of electricity and unreactive.

- Aluminium can be used in window frames as it is strong and light.

- As metal have common physical properties, different metals can have the same uses.

- Metals also share common chemical properties, e.g., most metals react with oxygen to produce a metal oxide. lithium+ oxygen produces lithium oxide

- In compounds that contain more than 2 elements, the element furthest to the right of the PT is placed last and the ending is changed to -ide.

sodium + oxygen produces sodium oxide

silver reacts with oxygen and turns black

iron and sulfur glow read when heated.

Metals react with halogens (element in group 7 - e.g.,fluorine, chlorine) to form a single, solid compound

E.g., zinc + fluorine produces zinc fluoride

Not all metal reactions take place at the same speed.

Catalysts

Some metals are used as catalysts to sped up chemical reactions.

A catalyst is a substance that speeds up a reaction without itself being changed.

e.g. zinc + sulfuric acid + copper (the catalysts to sped up the process) produces zinc sulphate and hydrogen.

- the cooper (catalyst) is recovered unchanged.

examples in everyday life: gas hair curlers contain platinum catalyst to sped up the reaction to produce/ release heat.

Only small amount of catalysts are needed as they are unreactive and can be recovered and used multiple times.

Metals

- Metals are on the left of PT

- Non- metals are the right of PT

- All metals share similar properties.

- Two best experiments to determine if a material is metal are 1) to test for thermal conductivity (heat star experiment) and 2) inserting a material into an electrical circuit.

- Most metals are non magnetic. The only magnetic metals are iron, cobalt and nickel (next to each other in PT)

- Alloy= mixture of mixture of a metal and another element. E.g steel is a alloy as it is a mixture of iron + carbon

- Alloys are stronger than pure metals.

- Pure metals are bendy as all the atoms are the same size, so the layers easily slide over one another.

- Alloys have atoms of different sizes so it is more difficult to slide over each other as they are not arranged in regular rows.

- This means all alloys are stiffer than pure metals.