Copy of Year 9 Mid Point Assessment Core Qs Chemistry only 24_25 - Chemistry Flashcards
What is an element?
Substance made from only one type of atom.
What is a compound?
Substance made from different types of atoms that are chemically combined.
What is a pure substance?
A substance where all the particles are the same.
What is a mixture?
Contains different elements or compounds which are not chemically combined.
What is a physical change?
Where the state changes but the chemical remains the same.
What is a chemical change?
Where a new chemical substance is formed.
What is a solution?
A mixture that contains a solute and solvent.
What is filtration?
Separating a solid from a liquid or gas
How do you separate salt from a mixture of salt water?
Evaporation of the water/distillation
What is chromatography?
A separation technique that separates based upon the solubility of a substance.
What is an atom?
A particle made of protons, neutrons and electrons
What are the three subatomic particles?
Protons, neutrons and electrons
How are the subatomic particles arranged in an atom?
Protons and neutrons in a nucleus, electrons travel around the nucleus in shells
What is between the nucleus and the shells?
Empty space
How can atoms be different to each other?
In the number of protons, neutrons and electrons they have
What charge does an electron have?
Negative charge (-1)
What charge does a proton have?
Positive charge ({+1)
What charge does a neutron have?
No charge(0)
Why do atoms have no overall charge?
The number of protons always equals the number of electrons in an atom.
What is the atomic number?
This is the number of protons.
What is the mass number?
This is the total number of protons and neutrons.
Which number identifies the element?
The atomic number.
What is the maximum number of electrons that the first shell can have?
2
What is the maximum number of electrons that the second shell can have?
8
What is the maximum number of electrons that the third shell can have?
8
Who described atoms as solid spheres that cannot be broken down in the early 19th century?
John Dalton
What name was given to an atom described as a ball of positive charge with negative electrons studded into it?
The plum pudding model
What name was given to Ernest Rutherford’s description of the structure of the atom?
The nuclear model
Who proposed that electrons orbit the nucleus in fixed shells?
Niels Bohr
In what order were the particles discovered.
Electron, proton, neutron
Who discovered the neutron in the 1930’s?
James Chadwick
How many different atoms are there?
118
How are atoms arranged in the periodic table?
In order of their atomic number
Where are metals found in the periodic table?
On the left of the periodic table
Where are non-metals found in the periodic table?
On the top-right of the periodic table
What are the veritical columns called?
Groups
What are the horizontal rows called?
Periods
What does the group number tell you?
The number of electrons in the outer shell
What does the period number tell you?
The number of electron shells
Why do elements in the same group of the periodic table have similar chemical properties?
Because they have the same number of electrons in their outer shell
Why were early periodic tables incomplete?
Not all elements had been discovered
How did John Newlands arrange the then known elements?
atomic weight
Why did Newlands periodic table not work?
It mixed up metals and non-metals in the same group. He left no gaps for elements that would be discovered later.
How did Dimitri Mendeleev overcome some of the problems of the early periodic tables?
He left gaps for unknown elements and predicted what their properties would be. In some places he changed the order based on atomic weights.
How are the elements arranged in the modern periodic table?
In order of their atomic (proton) number
What is another name for the group 1 elements?
The alkali metals
How many electrons do group 1 elements have in their highest energy level?
1
Why are group 1 elements stored under oil?
To prevent them from reacting with oxygen or water
What is the trend in reactivity as you go down group 1?
Reactivity increases down the group
alkali metal + water →
metal hydroxide + hydrogen
What is another name for the group 7 elements?
The halogens
What is the trend in reactivity as you go down group 7?
Reactivity decreases down the group
What is the trend in melting point and boiling point as you go down group 7?
The melting and boiling points increase going down Group 7
What is another name for the group 0 elements?
The noble gases
Why are the group 0 elements very unreactive?
This is because they all have a full highest energy level, giving them a stable arrangement of electrons.
What is the law of conservation of mass?
Atoms are not created or destroyed in a chemical reaction, they are just rearranged.
What do the small numbers in a chemical formula represent?
The number of a certain element in a substance
What is the chemical formula for hydrogen?
H2
What is the chemical formula for oxygen?
O2
What is the chemical formula for water?
H2O
What is the chemical formula for methane?
CH4
What is the chemical formula for carbon dioxide?
CO2
What is the chemical formula for Chlorine?
Cl2
What is a symbol equation?
It shows you what happens in a chemical reaction using chemical symbols and formulae
Why does a symbol equation need to be balanced?
There must always be the same number of atoms of each element on both sides of the equation
Which numbers must you not change when balancing?
You cannot change the little numbers (the formulae)
On which side of the equation are the reactants?
left-hand side
On which side of the equation are the products?
right-hand side
