Atoms elements compounds and mixtures Flashcards
Whats a compound
A substance containg two or more elements, which are chemically bonded
How can you separate compounds?
By chemical reactions or electroylsis
Which side of the equation are the reactants on?
The left hand side
What side of the equation are the products on?
The right hand side
What’s a mixture?
Two or more elements or compounds that aren’t chemically bonded
The components in a mixture still maintain their properties. True or False
True
What processes can be used to separate mixture?
Physical processes
.No chemical reactions are neccesary
What’s filtration used for?
Used to separate insoluble solids from soluble solids
Eg: sand and salt in water
What’s crystallisation used for?
Used to obtain soluble solids from a solution
Eg: salt from salt water
What’s simple distillation used for?
Used to obtain a solvent from a solution
What’s fractional distillation used for?
Used to separate mixtures in which the components have different boiling points
What’s chromatography used for?
Used to separate the different soluable, coloured components of a mixture
Eg: separating coloured dyes in a sloution
What was the earliest model of an atom thought to be?
Tiny spheres that couldn’t be divided into smaller particles
What was the name of the man that discovered electrons?
Thomson
What year were electrons discovered?
1898
What did Thomson discover?
Electrons
What is the overall charge of an atom
0
. Neutral
What’s the overall charge of an electron?
-1
.Negative
What’s the plum pudding model?
A ‘pudding’ of positive charge with ‘raisins’ of negative electrons dotted around
What experiment did Geiger and Marsden conduct?
They fired alpha particles at a thin sheet of gold
What happened in the Geiger and Marsden experiment? (gold foil)
Most of the positively charged alpha particles passed right through the atoms, but a small number were deflected back towards the souce
Who discovered the nucleus?
Rutherford
What did Rutherford determine?
That the positive charge in an atom must be concentrated in a small area
What model replaced the plum pudding?
The nuclear model
Who discovered that electrons orbit the nucleus in shells?
Bohr
Who proved the evidence of neutrons within the nucleus?
James Chadwick
Relative mass of a proton
1
Relative mass of a neutron
1
What does the atomic number of an element represent?
The number of protons in it
What’s the equation for the number of neutrons?
Mass number-atomic numer
What’s an isotope?
An element that has the same number of protons but a different number of neutrons
What happens to atoms when they loose or gain electrons?
They become an ion
How many electrons can the first shell hold in the first 20 elements?
Maximum 2
How many electrons can the second shell hold in the first 20 elements?
Maximum 8
Who created the modern periodic table?
Mendeleev
When did mendeleev create his periodic table?
1869
What elements are in group 0
Noble gases
Why are noble gases unreactive?
As they have a full outer shell
What elements are in group 1?
The alkali metals
How many electrons in an alkali metals outer shell?
1
Do alkali metals have high or low melting and boiling points?
Low that decrease down the group
They get more reactive further down the group
Why do alkali metals get more reactive further down the group?
As the outer electrons gets further away, meaning it’s easier to loose
What are alkali metals stored in and why?
Oil, as they can easily react with water and the air
What are the products when an alkali metal reacts with water?
Metal hydroxide
Hydrogen gas
Do group 1 metals have a high or low density?
Low density
What happens when alkali metals react with non metals?
They form ionic compounds
When this happens the metal ion loses one electron to form a metal ion with a positive charge
