Classification of Matter

Matter exist in 3 state- Soild, liquid and gas.

Solid has fixed shape, fixed volume and high density

Liquid has unfixed shapes, fixed volume and has moderate density

Gas has unfixed shape, unfixed volume and has low density

The inter-conversation of states.

Melting.

When a solid is heated, heat is absorbed causing particles to increase in energy and vibrate.

Boiling.

At boiling point, particles get enough energy to overcome the forces holding them together, causing them to break away from the liquid to form a gas

Evaporation.

Evaporation takes place at the surface of the liquid.

Evaporation takes place at all temperature.

Freezing.

At freezing point, liquid turns to solid.

Heat energy is given out

Temperature stays constant while liquid freezes as heat energy is released when particles slow down to take up fixed position in the solid.

Sublimation.

Process whereby inter-conversation between solid to gaseous state without passing through the liquid state.

Heat energy is absorbed when solid changes to gas

Heat is given out when gas change into a solid

Mass and Density

Definition of mass

Mass is a measure of the amount of matter in an object

The mass of an object is constant and does not vary from place to place

The SI unit for mass is kilogram (kg)

Tonnes(t)

Kilogram(kg)

Gram(g)

Milligram(mg)

1 t = 1000kg

1kg = 1000g

1kg = 1 divided by 1000 tonne

1g = 1000mg

1g = 1 divided by 1000kg

1mg = 1 divided by 1000g

An instrument used to measure mass is called a balance

Definition of weight

Weight depends on the mass of the object and the force of gravity. It can change as the force of gravity changes

For example, if an object is 6kg on earth, it is 1kg on moon.

The SI unit for weight is newton(N)

The instrument which is used to measure weight is called a spring balance

Definition of density

Density of a substance is defined as its mass per unit volume

Different materials have different densities

The SI unit for density is kilogram per cubic metre(kg/m to the power of 3)

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When the density of an object is less than that of the fluid(liquid or gas), the object will float.

When the density of the object is more than that of the fluid, the object will sink.

Some uses of density below

•The hydrometer. Measures the density of liquids. Used to test electrical strength of accumulator

•The lactometer. Used to test the purity of milk

•The plimsolls lines. Markings on the hulls of ships showing how deep the ships may be submerged in different types of sea water safely.

•Hot air balloon. Rises in the air. Hot air is less dense than air at ordinary temperature.

• Submarine. By pumping water in and out of it, the density of the submarine changes. Hence the submarine may float or sink in water.

Physical Quantities and Units

The basic quantities and Units are the System International of Units, also called the SI units.

It makes up of 7 base quantities and units. They are as below

Base quantity Base Unit

Name Symbol Name Symbol

time t second s

length l metre m

mass m kilogram kg

temperature T,0 kelvin K

electric current I ampere A

amount of substance n mole mol

luminous intensity I_v candela cd

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These SI units are used very accurately all around the world

All other physical quantities are known as derived quantities. Both quantity and its unit are derived from a combination of base units by using a defining equation

For example, acceleration= change in velocity(m s-1) divided by time taken(s)

Combining the units in the defining equation gives us the derived unit of acceleration

For very large or very small numbers, we can use standard prefixed with the base units. The followings are the prefixes

Prefix Symbol Multiplier

giga G 10 to the power of 9

mega M 10 to the power of 6

kilo k 10 to the power of 3

milli m 10 to the power of -3

micro µ 10 to the power of -6

nano n 10 to the power of -9

pico p 10 to the power of -12

femto f 10 to the power of -15

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There might be errors in the experimental methods or equipment where readings are either too big or too small.

For example, if your newton-meter reads 0.2 N with no weights on it, then your measurement of force will always be 0.2 N too large

These are called zero errors

Summary of topics covered in school

These are some of the topics I had covered in school

1) Physical Quantities and Units

2) Mass and Density

3) Classification of matters

4) Elements

5) Compound and mixture

6) Solution and suspension

7) Separation techniques

8) Cells

9) Photosynthesis

10) Respiration

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Sometimes, I will not be quite sure of some of the definitions of the science terms

eg. Suspension, solution, mixture, compound. I will mix up all of these terms.

eg. The periodic table. I will not know which is period and which is row. Also, I am not sure of the uses of the row and periods.

For the following posts, I will explain about the topics I had learnt

Reflections For Term 2 Test Results

For term 2, my results has been quite bad as I got a C6 for my test. This is because of not studying for the test beforehand. I feel that I had not worked hard for this test and the results were extremely terrible. Therefore, I feel that I must study harder for my science test next term.

What I wish to learn for Term 2

For term 2, I wish that I could learn more about the uses of the chemicals and what they could be used for. Also, I hope that I could do more of the Lab lessons.

Things I have learnt in my science lesson

In my science lesson, I learnt about the uses of the eqiupments and how to use it SAFELY. For example: When using the Bunsen burner, we should wear safety goggles to prevent the liquid to suddenly spill and go into my eyes. Also, we must turn off the gas tap when not in use as the gas is poisonous. I also learnt how to draw the equipments such as the flask, pipette, etc.