Simple model of atom

What is an element

This is a substance made up of atoms that contain the same amount of protons

What is a compound

This is a pure substance made from two or more elements chemically combined

What is a mixture

This is a combination of two or more substances that are not chemically combined

what processes could be use to separate mixtures

• filtration

• Evaporation

• Distillation

• Chromatography

what is filtration

This is used to separate an insoluble solid from a mixture of the solid and a liquid

How does filtration work

• a filter paper is placed in filter funnel over a beaker

• The mixture of insoluble applied and liquid is poured into the filter funnel

• The filter funnel only allows the liquid and soluble solid to pass through ( filtrate)

• And the insoluble solid is kept in the filter paper ( residue)

What is crystallization

This is used to separate a soluble solid from a solution

How does crystallization work

• the solution is heated allowing the solvent to evaporate leaving a saturated solution behind

• You can test if the solution is saturated by dipping a cold clean dry glass

• If the solution is saturated crystals will form on the rod when it is allowed to cool

• The saturated solution is allowed to cool slowly

• Crystals formed and removed by filtration

• They are washed with distilled water to remove impurities and allowed to dry

What is simple distillation

This is used to separate a liquid and soluble solid from a solution

How does simple distillation work

• the solution is heated and pure water evaporates creating vapor

• The vapor passes through the condenser where it cools and condensers turning into pure water collected in a beaker

• After all the water is evaporated only the solute is left

What is fractional distillation

This is used to separate liquids that are miscible with one another

How does fractional distillation work

• the solution is heated to the temperature of the substance with the lowest boiling point

• The solution will rise and evaporate first and vapor will pass through a condenser where they cool and condense turning into a liquid collected in a beaker

What is paper chromatography

This is used to separate substances that have different solubiliyies

How does paper chromatography work

• a pencil is drawn on chromatography paper and spots of the sample are placed on iy

• The paper is lowered into the solvent container

• Pencil line must sit above the level of the solvent so samples don’t wash into the container

• The solvent travels up the paper by capillary action taking some of the colored substances with it

• Different substances have different solibulities so will travel at different rates

Describe John daltons atomic theory

• presented in 1803

• Matter is made of atoms which are tiny particles that can’t be created destroyed or divided

• Atoms of the same elements are identical and atoms of different elements are different

• Different atoms combine to form new substances

When was the electron discovered

1897 by J.J Thomson

What is the plum pudding model

• using a cathode ray tube J.J Thomson conducted an experiment identifying the electron as a negatively charged subatomic particle proving atoms are divisible

• Based on the experiment Thomson proposed an atomic model that depicted negative electrons spread around and surrounded by positive material ( plum pudding)

What did the Rutherford scattering experiment show (1909)

• Rutherford shot a beam of positively charged particles at a sheet of gold foil

• Most of the particles went straight through the gold foil implying that atoms were mostly empty space

• Some were scattered and few were deflected directly back which led to the discovery that an atoms mass is concentrated in the nucleus

• Some were deflected slightly implying that the nucleus was positively charged

When was the proton discovered

1920 by Rutherford

What is the Bohr model

• in 1913 Niels Bohr further developed the nuclear model by proposing that electrons orbit the nucleus is fixed shells

When were neutrons discovered

1932 by James Chadwick

What are the charges of the sub atomic particles

• neutrons - 0

• Protons - +1

• Electrons- -1

  atoms are neutral overall

What is the radius of atoms

0.1 nanometers

What is the relative mass of sub atomic particles

• neutron -1

• Proton- 1

• Electron- negligible

What is atomic number

This is the number of proton in the nucleus of an atom

What is mass number

This the total number of neutrons and protons in the nucleus of an atom

What is an isotope

These are atoms of the same element with the same atomic number but different mass number ( neutrons)

What is relative atomic mass

The average mass of the atom of an element relative to the mass of an atom of carbon-12

How is the periodic table arranged

• periods : horizontal rows

• Groups: vertical columns

What do elements in the same group have in common

The number of outermost electrons

What do elements in the same period have in common

Same number of electron shells

How are element arranged on the periodic table

Arranged in order of atomic number

How was the early periodic table arranged

In order of atomic weight because sub atomic particles had not been discovered

How does metallic character change down the group and across the period

It increases as down the group and decreases as you move across a period left to right

What are the properties of metals

• 1-3 outer shell electrons

• Good conductor of electricity

• Metallic bonding

• Solid at room temperature except mecury

• High melting and boiling point

• Hard and malleable

• React to form basic oxides

What are the properties of non metals

• 4-7 outer shell electrons

• Poor conductors of electricity

• React to form acidic oxides

• Low boiling and melting point

• Flaky and brittle

• Different states at room temperature

What are the chemical properties of noble gasss

• Non metals

• Monoatomic

• Colorless and non - flammable gases at room temperature

• Low boiling and melting point

how does the boiling and melting point of noble gases change down the group

They increase down the group because the atoms get larger as you move down the group and their RAM increases meaning the intermolecular forces become stronger therefore needing more energy to overcome them

What are the properties of group 1 elements

• they are soft metals

• They have low densities and low boiling points

• Their melting points decrease as you go down the group

What happens to the reactivity of group 1 elements

The reactive increase as you go down the group because when group 1 elements react they need to lose one electron to become stable as you move down the group the atoms become bigger meaning the force of attraction between the outermost electrons and nucleus is weaker and less energy is required to overcome the forces of attraction

What happens when alkali metals react with oxygen

They form metal oxides which is a dull coating that covers the surface of the metal

How do alkali metals with water

• lithium- relatively slow reaction, fuzzing, lithium moves on the surface of water

• Sodium - more vigorous fizzing, moves rapidly to the surface of water, dissolves quickly

• Potassium- reacts more vigorously, burns with lilac flame, moves rapidly to the surface and dissolves very quickly

What are the properties of group 7 elements

• poisonous non metals

• Diatomic

• They form halides when they gain electrons in reactions

• Boiling and melting points increases as you do down the group

What happens to the reactivity of halogens

The reactivity decrease down the group because the number of shells of electrons increases down the group and halogens gain an electron to form a negative ion sit obtain a full outer shell this means the increased distance from the outermost electrons to the nucleus as you go down the group makes halogens less reactive because the force of attraction between the nucleus and outermost shell decreases making it harder to gain electrons

What is a displacement reaction

This occurs when a more reactive halogen displaces a less reactive halogen from an aqueous solution of its halide

What are the properties of transition metals

• thry are lustrous

• Good conductors of heat and electricity

• High density and high melting points

• They create colored compounds

• They can have more than one oxidation state

• They are used as catalyst

What are the difference between transition metals and alkali metals

• group 1 form ions with +1 charge while transition metals form ions with variable charges

• The transition metals are harder and denser

• Transition metals have higher melting points

• Transition metals are less reactive