CHEMISTRY C1
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True or False? Metals are found on the right hand side of the stepped line in the periodic table?
False - Non-metals are found on the right and metals are found on the left of the stepped line.
What are the 7 diatomic elements?
Iodine - I2 Bromine - Br2 Chlorine - Cl2 Fluorine - F2 Oxygen - O2 Nitrogen - N2 Hydrogen - H2
What is a compound?
A substance that contains two or more elements that are chemically combined.
In compounds made up of non-metal elements only, the second word of the compounds name will always start with mon, di or tri. E.g. Carbon dioxide.
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What is an ion?
A charged particle formed when an atom, or a group of atoms, loses or gains electrons.
What’s important with the number of ions when working out the formula of a compound?
The numbers of ions in a formula must give an equal number of positive and negative charges.
What are reactants?
Substances that react together in a chemical reaction to form a product.
What does the law of conservation of mass state about mass in a chemical reaction?
No atoms are lost or made during a chemical reaction, so the total mass of the products is equal to the total mass of the reactants.
What does a pure substance contain?
Consists only of one element or one compound.
What is a mixture?
Consists of two or more different substances, not chemically joined together.
What is filtration used for?
To separate an insoluble solid from a liquid.
How does crystallisation work?
When the solution is warmed, some of solvent evaporates leaving crystals behind.
What is distillation used for?
To separate a solvent from a solution.
How does distillation work?
The dissolved solute has a much higher boiling point than the solvent. When the solution is heated, solvent vapour leaves the solution. It moves away and is cooled and condensed.
How does fractional distillation work?
• Vapours rise through a column which is hot at the bottom, and cooler at the top • Vapours condense when they reach a part of the column that is below the temperature of their boiling point • Each liquid is led away from the column
What is fractional distillation used for?
To separate different liquids from a mixture of liquids. It’s useful for separating different fractions from crude oil.
What is paper chromatography used for?
To separate mixtures of soluble substances.
What are the two phases that chromatography relies on?
• The stationary phase, which in paper chromatography is very uniform, absorbent paper • The mobile phase is the solvent that moves through the paper, carrying different substances with it
What can a paper chromatogram be used for?
To identify substances by comparing them with known substances.
How can relative atomic mass be written as a symbol?
Ar
How do you calculate relative atomic mass?
Ar = Total mass of atoms/total number of atoms (Mass x abundance) + (mass x abundance)/ 100
Which scientist published the first periodic table in 1869?
Dmitri Mendeleev - A Russian chemist
What is meant by an electronic structure?
The way in which electrons are arranged in an atom.
What does the number of electrons in the outermost shell tell us about the element?
The group number that the element is in.