Science Yr 10 Notes Essay

Submitted By smelleste
Words: 3299
Pages: 14

Science Skills

How to Write a Report
1. Aim: The question you are asking.
2. Hypothesis: ‘If the (independent variable) increases, then the (dependent variable) will increase/decrease/stay the same.’
3. Method: Should be numbered or dot points
4. Results: Either in a table or graph. Can be observations or measurements or both.
5. Conclusion: Answer the Aim.
6. Evaluation: Talk about accuracy, reliability, validity.
7. Safety: State the piece of safety equipment and why you need it.

Variables
In every experiment you change one thing and measure one thing. Everything else is kept the same.
• Independent Variable: What you change in the experiment (e.g. area of parachute sail)
• Dependent Variable: What you measure in the experiment (e.g. time taken for parachute to fall to the ground)
• Controlled Variables: Everything else you should keep the same (e.g. weight of object in parachute, same height from which parachute is dropped, same amount of wind)

R.A.V
Reliability = Repeats: Depends on how many times you do the experiment.
Accuracy = Apparatus: Depends on the Person doing the experiment and the Equipment.
Validity = Variables: Are you actually testing what you want to? Are all other variable controlled except for the one you are changing and measuring?

Chemical Reactions

Definitions
Atom: the smallest unit of an element
Element: a piece of matter that is made up of 1 type of atom; it is pure.
Molecule: 2 or more non-metal atoms covalently bonded
Compound: 2 or more different atoms bonded together
Ionic compound: a metal and non-metal bonded together
Covalent Compound: 2 non-metals sharing electrons.

Naming Compounds
1. Write the first element down. For transition metals, the charge is indicated using roman numerals
2. Write the second element and add the suffix –ide
3. Add a number prefix if for covalent compounds

Prefixes Used to Name Covalent Compound 1. Mono (note: don’t have to write mono for the first element)
2. Di
3. Tri
4. Tetra
5. Pent

6. Hex
7. Hept
8. Oct
9. Nona
10. Dec

What is a chemical reaction?
A chemical reaction occurs when at least one new substance has been formed
Reactant  Product • Reactant: present at the start
• Product: new substance that is formed

How can we tell?
• Product looks or acts differently from reactants.
• A gas is produced.
• A solid is produce or dissolved.
• Change in colour.
• Heat is given off (exothermic).
• Heat is absorbed (endothermic).

Balancing Equations
• You can only change put coefficients in front of the reactants or products. Do not change transcripts
• There should be the same amount of atoms on the reactant side as there is on the products side
• Treat polyatomic ions as a single unit

States
• (s) for a solid substance
• (g) for a gas
• (l) for a pure liquid
• (aq) to show that a substance is in aqueous solution (i.e. dissolved in water).
Polyatomic ions (radicals)
A polyatomic ion is made up of more than one type of atom. It cannot exist by itself however, will retain its identity in chemical reactions
Ion name Formula
Ammonium NH4+
Nitrate NO3-
Sulfate SO4-2
Carbonate CO3¬-2
Hydroxide OH-
Phosphate PO4-3

Acids
Acid Names Chemical Formula
Hydrochloric Acid HCL
Sulfuric Acid H2SO4
Nitric Acid HNO3
Acetic Acid in vinegar
Lactic Acid In sore muscles
Citric Acid In fruits

Bases
Base name Chemical formula
Sodium Hydroxide NaOH
Magnesium Hydroxide Mg(OH)2
Sodium Oxide Na2O

Why do Chemical Reactions Occur?
• Spontaneous reactions: these normally happen and only require small amounts of energy to get started but keep going themselves. E.g. rusting of iron
• Non- spontaneous reactions: these require continual energy input to keep them going

Types of chemical reaction
Corrosion
• The presence of salt will speed up the corrosion process. Salt acts as a catalyst
Metal + Oxygen + Water  Metal Oxide
Iron + Oxygen + Water  Iron…