C1 Flashcards
What are all substances made up of?
Atoms
How many types of atoms are there?
About 100
What is the smallest part of an element?
The atom
What is an element ?
A substance made up of only one type of atom . Can have many different properties( gas ,solid , shiny , metal)
Why are there chemical symbols?
Need to be understood in all languages
What are the columns called and what do they contain?
Groups , each group contains elements with similar chemical properties
What divides the metals and non metals?
The stair case
What state are the vast majority of substances?
Compound
What is a compound?
Different types of atoms bonded together
What is a molecule?
A group of two or more atoms bonded together
How is a compound formed ?
A chemical reaction
What bonds do compounds have ?
Chemical bonds , holding it tightly together.
How are atoms of each element represented in the periodic table?
With a chemical symbol , eg. O for oxygen
What does the periodic table show?
All the elements
What does a chemical reaction always involve?
The formation of one or more new substances , and often a detectable energy change.
How can a compound be separated?
Through a chemical reaction
How can compounds be represented ?
Use the symbols of the atoms
Hydrogen + oxygen —> water , what are the reactant[s]and what are the product[s]
Hydrogen + oxygen , reactants
Water , product
What do symbol equations help you see?
The amount of a substance involved
What is the law of conservation of mass?
Atoms cannot be created or destroyed
What does it mean for an equation to be balanced?
The total mass of the products is equal to the total mass of the reactants. Energy cannot be created or destroyed so equations must be balanced
What are the state symbols?
S=solid
G=gas
L=liquid
AQ=aqueous
Balance this equation?
H2 + O2 —-> H2O
- List out the mass on both sides and add until you get the same on both sides
Answer: 2H2+O2 —> 2H20
What is a mixture ?
Made up of 2 or more elements or compounds not chemically bonded together . The chemical properties of each substance remains unchanged.
Features of a compound?
- Fixed composition
- chemical reactions must take place to separate elements in a compound
- chemically bonded
Features of a mixture?
- No fixed composition
- can be separated more easily
- no chemical bonds
What are the separation techniques?
- filtration
- crystallisation
- distillation
- chromatography
What is filtration ?
Used to separate substances that are insoluble in a particular solvent from those that are eg. Sand and salt in water
What does soluble mean ?
Able to be dissolved in water.
What is a solvent?
The liquid in which a solute is dissolved to form a solution.
What is distillation?
Distillation collects the solvent when a solid and solvent are separated , rather than evaporating it.
What does chromatography do?..
Mixtures of substances can be separated using it.
Steps in chromatography?
- Draw a horizontal line near the bottom of the paper
- Place a dot of each colour on the line using a capillary tube
- Place the paper in a beaker so that the bottom of the paper is just in the water
- Use the ruler to measure the distance travelled by each dot from the starting line and the distance the water has travelled to find the retention factor
How to calculate the retention factor?
Distance moved by substance/ distance moved by solvent