PERIODIC TABLE

What are columns in the periodic table called?

groups

What do elements in the same group have?

the same amount of electrons in their outer shell

What are elements in the same row called?

periods

What do elements in the same period have?

the same number of electron shells

How were elements arranged in the early 1800s

mass number

What was the law of octaves?

a list of elements placed in order of increasing atomic mass, noticing that every 8th element has similar chemical properties

Who came up with the law of octaves?

John Newlands

Why did many scientists not accept Newlands of octaves?

many new elements were still being discovered and did not fit in the table, for example not having similar properties

What changes did Mendeleev make to the periodic table?

sorting the elements into groups based on their properties

Why would some elements end up in the wrong column?

the atomic mass was wrong due to isotopes

What did Mendeleev do whenever the elements were in the wrong column?

he switched the order of the elements

How else did Mendeleev keep elements with similar properties together?

he left gaps for elements yet to be found

How are elements arranged now?

By atomic number with elements with similar properties in the same groups

What is a chemical property?

the type of chemical reactions elements undergo, what they react with and how vigorous is the reactions are

Why are group 1 elements so reactive?

because they have one electron in their outer shell which is readily lost

What are the properties of group 1 metals?

• they have low densities

• they are very soft

• they have low melting and boilings point

• the reactivity increases as you descend the group

• they are highly reactive

Why does reactivity increase the further down group 1 you go?

the atoms get larger and the outer electron gets further from the nucleus so the attraction between the nucleus and outer electron gets weaker so its easier for that electron to be lost

What happens when group one metals react with cold water?

they produce a metal hydroxide and hydrogen gas

Why are group 1 metals called alkali metals?

because metal hydroxides are alkaline substances

What happens when lithium reacts with water?

it fizzes on the surface

What happens when sodium reacts with water?

fizzes, melts and produces a yellow flame

What happens when potassium reacts with water?

it fizzes, melts and produces a purple flame

What are the properties of metals?

• hard

• good conductor

• high melting point

• shiny

• malleable

What are the properties of non metals?

• brittle

• good insulator

• low melting point

• dull

• soft

What does dense mean?

particles are packed tightly together

What does a high melting point mean?

require very high temperatures to be melted

What is a thermal conductor?

it allows heat energy to pass through it

What is an electrical conductor?

it allows electrical current to pass through them

What does malleable mean?

can be bent and shaped without breaking

What does ductile mean?

it can be easily drawn into wires

Similarities between transition metals and group 1 metals?

• conductivity

• shiny when freshly cut

Differences between transition metals and group 1 metals?

transition metals have:

• higher melting points

• higher densities

• greater strength

• greater hardness

• form coloured compounds

What are group 0 elements often referred to as?

noble gases

What are the properties of noble gases?

• colourless at room temperature

• monoatomic

• inert

• last gases to be discovered

What does monoatomic mean?

Their gases are made up of single atoms

What does inert mean?

completly unreactive

What happens as you descend group 0?

boiling point, melting point and density all increase

What are group 7 usually called?

halogens

What kind of molecules are halogens?

diatomic

What happens as you descend group 7

melting point and boiling point increases

Why does melting point and boiling point increases as you go down the halogens?

increasing intermolecular forces as the atoms become larger, so more energy is needed to overcome these forces

What are the halogens?

• fluorine

• chlorine

• bromine

• iodine

Properties of fluorine?

highly reactive pale yellow gas

Properties of chlorine?

poisonous green gas

Properties of bromine?

poisonous orange brown liquid which gives off an orange vapour

Properties of iodine?

grey solid which gives off a purple vapour

What happens to the reactivity as you descend group 7?

it decreases

What is the most reactive halogen?

fluorine

Why does reactivity descend as you go down group 7?

as you go down the group atoms have more electron shells, more shells mean more shielding so an electron is less easily gained

What happens when a group 7 element gains an electron?

they form -1 ions

What is a displacement reaction?

when a more reactive element replaces or pushes out a less reactive element from a compound

What happens after a displacement reaction?

the less reactive element is left pure and uncombined

How does displacement work with the halogens?

more reactive halogens can displace less reactive halogens from their compounds