TOPIC 1 : atomic structure and the periodic table

What is a mixture ?

A mixture is 2 or more elements/compounds that are not chemically combined

What is a compound?

A compound is 2 or more elements chemically combined

What processes can mixtures be separated by ?

Describe the plum pudding model by JJ Thomson

The plum pudding model is a ball of positive charge with negative electrons embedded in it

What was the alpha particle scattering experiment by Rutherford? + What did it show ?

• mass of an atom was concentrated at the centre (nucleus) and that the nucleus was charged

• most (almost all) went through the gold foil & were not deflected —> atom mostly empty space

• few (not many) bounced directly back —> The atom's dense core (nucleus) must be very small and positive

• several (some) passed through the gold foil & were deflected —> The nucleus must be positive (law of repulsion)

Describe the Bohr model of the atom

Bohr suggested that electrons orbit the nucleus at specific distances

What did James Chadwick prove ?

James Chadwick provided the evidence to show the existence of neutrons within the nucleus

What does the atomic number show?

The atomic number = the number of protons

What does the number of protons equal ?

What is the mass and charge of a proton?

A proton has a 1+ charge and a mass of 1

What is the mass and charge of a electron ?

A electron has a 1- charge and a very small mass

What is the mass and charge of a neutron ?

A neutron has 0 charge and a mass of 1

What is the mass number ?

The mass number is the sum of protons and neutrons in an atom

How are elements in a periodic table arranged?

They are arranged in order of atomic (proton) number

What do elements in the same column have?

They have similar chemical properties and the same amount of electrons in their outer shell

Describe Mendeleev’s early periodic table

• He ordered his table in order of atomic mass

• Left gaps for elements that he though had not been discovered yet

How did John Newlands order his table ?

He ordered his table in order of atomic weight

What did knowledge of isotopes help explain the order?

The knowledge of isotopes made it possible to explain what he order based on atomic weights was not always correct

What do metals react to form?

Metals are elements that react to form positive ions

Do non-metals form positive ions?

What is Group 1 called ?

Alkali metals

How do group 1 metals react in water ?

Metals in group 1 react vigoroumly with water to create an alkaline solution and hydrogen

How do group 1 metals react in oxygen ?

They create a oxide

How do group 1 metals react in chlorine ?

They form a white precipitate

Does the reactivity of elemtns increases down the group (in group 1 ) ?

Lily and Charles Say Yes-OK Please Like Comment OR Copper Gary

Lithium - Crimson flame

Sodium - Yellow-Orange flame

Potassium - Lilac flame

Calcium - Orange-Red flame

Copper - Green flame

What is group 0 called ?

They are the noble gases

Describe the reactivity of group 0

They are unreactive and do not easily form molecules as they already have a full outer shell (stable)

Do the boiling points of the noble gases increases as it goes down the group?

What is group 7 called?

They are the halogens

What are halogens

They are non-metals and exist as molecules made of pairs of atoms

What type of elements react to form ionic compounds ?

Metals and Non-metals

What type of elements react to form covalent compounds ?

2 non-metals and it is a shared pair of electrons

What happens as u go down group 7 ?

The relative molecular mass , boiling point and melting point all increase

Why does reactivity decrease as you go down group 7 ?

• the halogens react by gaining an electrons (for a full outer shell)

• number of shells increase down the group so the lower elements down the group attract electrons from other atoms. less , so they cant react as easily

What are the typical properties of transition elements?

• they are good conductors of heat and electricity

• they can be hammered or bent into shape easily

• they have high melting points (but mercury is a liquid at room temperature)

• they are usually hard and tough

• they have high densities