Atomic Structure Flashcards
What is an Atom?
> The smallest particle of a chemical element that can exist.
What is an elememt?
> A substance that is made from only one type of atom.
What is a compound?
> Contains two or more elements chemically combined in fixed proprotions
What is a Mixture
> They have different elements or compounds not chemically combined together.
What is a molecule?
> Has any elements chemically joined.
Explain Filtration?
> It separates an insoluble from a liquid
useful for separating sand from a liquid
It works because the filter paper has holes which are large enough to let small molecules and dissolved ions.
Explain the method to carry out Filtration?
1)One beaker contains a mixtures of solids and liquids, other containing funnel with filter paper.
2)The solid and liquids is poured into the funnel paper.
3)The liquid drips through the filter paper but the solid particles are caught in the filter.
Explain Crystallisation?
> It separates a soluble solid from a liquid
Produces crystals from a solution
Explain the method to carry out Crystallisation?
1)A solution is places in an evaporating basin and heated within a Bunsen burner
2)Volume of solution decreases because the water has evaporated.
3)All water has evaporated, leaving solid crystals behind.
Explain Simple Distillation?
> To separate a liquid from a dissolved solid
Useful for producing pure water from sea water.
Explain the method to carry out Simple Distillation?
> Salty water is heated
The water vapour cools the condenser and drips into the beaker.
The water has condensed and now in the beaker, the salt stays behind
What was the first discovery of electrons?
> John Dalton experiments led to the idea that atoms were very small sphere which can’t be divided.
What did JJ Thomson Do?
> He discovered the ‘electrons’ and made the plum pudding model which suggests atoms were spheres of positive change with negative charged embedded in it.
What did Rutherford Do?
> Alpha particle scattering experiment.
What did the Nuclear Model prove?
> Mass of atoms were concentrated in a charged nucleus.
It proved electrons orbited a Nucleus.
What happened after the Nuclear Model?
> Niels Bohr proposed electrons orbit nucleus at specific distances in fixed energy levels.
Later it was proposed that it was positive charge of nucleus which could be subdivided into particles of positive charge?
What did James Chadwick?
> Provided evidence for the existence of neutrons
What is Relative Atomic Mass?
> The weighted mean of mass of an element, taking into account all of the different isotopes and their relative abundance.
What is the formula for Relative Atomic Mass?
100
How are periodic tables arranged now compared to before?
> Early periodic table=atomic weight.
Now=atomic number
Outline the history timeline of the Periodic Table
1)Law of Triad-arranged by similar reactivity
2)Law of Octaves-Realised every 8 was similar but failed
3)Mendeleev-Started with atomic weight, left gaps for the future to find.
What is a ‘group’?
> Elements with similar chemical properties.
What is a ‘period’?
> Each row in the table
What are the properties of the Noble gases (Group 0)?
> Full Outer shell
Don’t do reactions
Don’t form molecules
Colourless gases
Low Bioling Point
Atomic mass increases down the group
Density increases
B.P. increases
What are properties of Alkali Metals (Group 1)?
> Low Density
Soft
Shiny when cut
Metals
Always lose 1 electron
Very reactive
Reactivity increases as you go down
What is the reaction with Alkali Metal + Oxygen?
> Room Temp: Colour change from shiny to white.
Hot: Burning vigorously farming white smoke.
What is the reaction with Alkali Metal + Chlorine?
> Very vigorous, product a metal chloride= slat.
Dissolves easily to make colourless solutions.
What is the reaction with Alkali Metal + Water?
> Very vigorous, fizzing, floats in water and dissolves solution is alkaline, metal blast releasing lilac flame.
What are the properties of the Halogens (Group 7)?
> Non-Metals
Low M.P. and B.P.
B.P. and M.P. increases
They always gain
What is the trend in reactivity in Group 7?
> The more you go down the less reactive
The closer the nucleus is, the easier to attract electrons
The more down you go electrons are further away from the nucleus, the harder it is to attract.
Harder to gain an electron=less reactivity.
