Atomic structure and the periodic table

What is each atom made up of

smaller particles

• nucleus → protons and neutrons

• Shells → electrons

What’s the relative mass for a proton

1

What’s the relative mass for a neutron

1

What’s the relative mass for a electron

Tiny

What’s the church of a proton

+1

What’s the charge of a neutron

0

What’s the charge of an electron

-1

What is most of an atom

Empty space

In an atom, why is there no overall charge

The number of protons and electrons cancel out so overall is neutral

What is an ion

Where an atom has lost or gained electrons so the charges are now longer balanced

What is the atomic number

The proton number i

What is the mass number

The number of protons and electrons in an atom

What particle determines what element an atom is

Protons

What are isotopes

The same element that has the same number of protons but a different number of electrons

What is relative atomic mass

Average mass of all the isotopes that make up an element

What is abundance

How rare/ common the isotope is

What’s the equation for relative atomic mass

Sum of (isotope abundance x isotopes mass) / sum of abundance of all isotopes

What are molecules

• A group of 2 or more atoms, held together by chemical bonds e.g oxygen

• can contain multiple different elements e.g H2O

What’s a compound

A substance that contains two or more DIFFERENT elements held together by chemical bonds e,g CO2 or H2O

What is a mixture

2 or more substances not chemically combined together

If you out sand in water and it doesn’t dissolve what does it make

A mixture

If you have a liquid and a soluble solid what does this make

A solution

What is filtration

When u separate insoluble solids from liquids

• fold the filter paper into a funnel and place into a beaker

• Pore the mixture in to the filtration paper

How does filtration paper work

Has tiny holes that liquid can pass through but not solids

How do you separate a soluble solid from a liquid

• evaporation or crystallisation

How do you carry out evaporation

• Place evaporating dish on a tripod over a Bunsen burner

• Slowly heat solution with Bunsen burner

• solvent will slowly start to evaporate and get more concentrated

• After a while, crystals will start to form as it is so concentrated and eventually all of the solvent will disappear

• Left with dry crystals in the solid

What are the benefits of evaporation

• easy

• Quick

What’s a con of evaporation

• some solids will decompose when heated→ thermal decomposition

What technique do you use to stop the solution from thermal decomposing

• use crystallisation

  1. Place solution in evaporating dish

  2. Place evaporating dish in water bath to gently heat solution

  3. Once majority of solvent evaporated you start to see crystals forming in solution

  4. Stop heating and leave to cool as solids are less soluble at colder temperatures

  5. Filter out solutions from remaining solution using filter paper and funnel

  6. Dry out crystals by leaving them somewhere warm or in oven

What are the steps for simple distillation

1. Solution is heated, usually using a Bunsen burner

2. The liquid in the mixture evaporates into a gas

3. Th3 gas is cooled by a condense and condensed back into a liquid, which then flows into the beaker

What does fractional distillation seperate

Several liquids that have the same boiling points

What is the process of fractional distilation

• heat is applied and the liquid with the lowest boiling point evaporates and condensed into a beaker

• If other liquids evaporate by chance, they condense in the fractionating column back into the flask

• The temperature is altered to repeat the process for the second liquid

• The three liquids are separated based on different boiling points with the 3rd remaining in the flask

How would you isolate pure water from saltwater

Simple distillation

What’s the atomic theory (1)

Everything is made up of tiny particles that can’t be broken down any further and separated by empty space

→ proposed by Democritus

What was the solid sphere theory (2)

Different types of spheres made up different elements and atoms were solid spheres

→ preposed by John Dalton

What was the plum pudding model (3)

Positive ball of charge with electrons embedded in it

→ preposed by J.J Thompson

Proved atoms weren’t solid spheres and contained electrons

What was the alpha particle experiment (4)

• Rutherford took positively charged alpha particles and fired them at a thin sheet of Gold

• The idea was that the positive charge in the gold atoms were genuinely spread out the alpha particles should pass straight through the sheet because the weak spread out positive charge wouldn’t be strong enough to effect them

  what really happened:

• some alpha particles deflected to the side or back the way they come → proved J.J Thompson theory wrong

What did the alpha particles lead Rutherford to suggest (4)

The nuclear model

→ instead of a general field of positive charge there was a compact nucleus, containing all the positive charge of the atom . The negative charge was a cloud around the nucleus

However the flaw was there was nothing stopping the negative cloud of electrons running into the protons so the atom should automatically collapse

What did Neil’s hour suggest (5)

• electrons orbit the nucleus, held in shells

• Orbiting of electrons prevent atom from collapsing

What did James Chadwick discover (6)

Neutrons

What order were the particles in an atom discovered

• electrons (Neil’s Bohr)

• Protons (earnest Rutherford)

• Neurones (James Chadwick)

In order for atoms to be stable, what do they need

A full outer shell

• if they don’t they have to react with another element to gain or lose electrons to gain a full

How many electrons are in shell 1

2

How many electrons are in shell 2 and any after

8

How is the period table ordered

In order of increasing atomic number

What are periods in a periodic table

Rows

What are groups in a period table

Columns

What did Dimitri Mendeleev do

Made the periodic table

Why do numbers in the same group all have same properties

All have the same numbers in the outermost shell and is what determines how an element reacts

Are there more metals or non metals

Metals

Why are Nobel gases unreactive

Has no electrons in it’s outer shell so is already stable

What do atoms of the same period all have the same number of

Shells

What do metals form when they react and why

Form positive ions

It takes less energy to lose electrons in the outer shell as there are only a few

What do meta,s form when they react

They either form negative ions or don’t form ions

It takes less energy to gain electrons to make a full outer shell

Why does group ones reactivity increase as it goes down the group

• The outermost shell is gets further away from the nucleus

• The positive nucleus holds the electrons in place

• The further away the electron is from the nucleus the weaker the force of attraction

• The atom loses the electrons easier and forms a positive ion

What type of bonds do metals have

Metallic bonds → very strong and responsible for metals physical properties

What are physical properties of metals

• strong

• Malleable

• Conductors of heat and electricity - why they are used in wires

• High melting and boiling points

• Shiny

• Sonorous

What are the physical properties of non metals

• brittle

• Dull in colour

• Low melting and boiling points

• Lower densities

What are the extra properties transition metals have

• can form more than one ion → can be different colours

• Catalysts → e.g iron in the harbour process

What are catalysts

Substances which increase the rate if a chemical reaction without being used up themselves

What are the alkaline metals (group 1) properties

• soft

• Low density

• Low melting point

When are the trends in the alkaline groun

• gets more reactive as you go down the group

• Melting and boiling points decrease

How do alkaline metals react in water

Reacts vigorously

Alkaline metals + H2O → metal hydroxide + hydrogen gas

• from potassium down it releases so much energy it ignites

How do alkaline metals react with chlorine

Reacts vigorously (as you go down the group)

Alkaline metal + chlorine → metal chloride

How do alkaline metals react with oxygen

Alkaline metals + oxygen → metal oxide

The type of oxide depends on the type of metal

When sodium reacts with oxygen what 2 products can be formed

• sodium oxide Na2O

• Sodium peroxide Na2O2

When potassium reacts with oxygen what 2 products can be formed

• potassium peroxide K2O2

• Potassium superoxide KO2

What is fluorine (halogen)

A poisonous yellow gas

What is chlorine (halogen)

poisonous green gas

What is bromine (halogen)

Reddy brown volatile Posinous liquid

What is iodine

grey solid that can also form poisonous purple vapours

• also used as an antiseptic

What do halogens exist as

Diatomic molecules → means 2 atom molecules

They do this by sharing electron and firming a covalent bond

Halogens can also form covalent bonds with other non metals - these compounds are knows as simple molecular structures

What are the trends for the halogens (group 7)

• reactivity increases as you go up the group

• Melting and boiling point decrease as you go down the group

Why does the reactivity decrease as you down the halogen group (group 7)

• as you go down the group the outer most shell gets further and further away from the positive nucleus

• Attractive force needed to pull in another electron from an atom gets weaker

• Halogen can’t attract another electron it can react so elements like iodine are the least reactive

What is a halogen called when it gains an electron (becomes a 1- ion)

Halide

What are displacement reactions

A more reactive element displacing s less reactive one

• more reactive halogens will displace a less reactive halogen

Everything about Nobel gases:

• group 0

• Colourless gases

• Unreactive (inert) as already have a full outer shell so are stable

  → why they also exist as single atoms

• Non-flammable

• Boiling and melting point increases as you go down the group