Trial SC Hints

-Newton’s 1st law (a force must be applied to change the speed or direction of an object)

  • Newton’s 1st law of Motion (also known as the law of inertia)
  • An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

-Laboratory safety rules

  • No student may enter a laboratory or preparation room except under the direct supervision of the teacher in charge.
  • The wearing of thongs, sandals, open or other un-protective footwear will not be allowed in any science laboratory at any time. Suitable leather or vinyl shoes are the only acceptable footwear in the laboratory.
  • Many materials in the laboratory are dangerous and must be used for the purpose stated by the teacher in charge.
  • Do not try experiments on your own. Do only the experiments assigned according to the instructions given by the teacher in charge.
  • Never taste chemicals. Smell chemicals only when instructed to do so and then cautiously in the correct manner.
  • Never drink from any taps or any vessels in the laboratory.
  • Always move carefully in a laboratory, and never run.
  • Never leave a Bunsen burner on when not in use.
  • Gas and water taps and electrical outlets are not to be used unless directed by the teacher in charge. Interference and/or damage to such could be dangerous and offenders will be severely disciplined.
  • All accidents (no matter how slight) or breakages must be reported at once to the teacher.
  • When heating chemicals in a test-tube, point the test-tube away from people. Never look directly into chemical experiments.
  • No bags, ports etc. are to be taken into laboratories.
  • Before leaving a laboratory, all work areas must be clean and tidy, and any equipment used must be returned to its proper place.
  • No misbehaviour will be tolerated in the laboratory. Students will be banned from practical work for persistent foolish behaviour.

-Parts of a wave (amplitude, wave length)

  • Amplitude:- The amplitude of a wave is the distance from the crest, or trough to the rest position. It is the maximum amount of displacement that the wave has.
  • The wavelength of a wave is the length of one complete wave cycle. This means, the length from crest to crest or tough to trough, from the rest position over a crest and trough and back to the rest position, or any two other point that are one complete wave cycle.

-Know how to read scaled pictures

-Parts of an atom (proton, neutron, electron) and where in the atom they are and their charge.

  • Proton – Protons have a positive (+) charge and are located in the nucleus of the atom.
  • Neutron – Neutrons have a neutral charge and are also located in the nucleus of the atom
  • Electron–Electrons have a negative charge (-) and are located in a shell circling outside the atom. The first shell can hold up to two electrons; the second can hold up to 8, third can hold up to 18, fourth can hold up to 32 and fifth can hold up to 50. (2, 8, 18, 32, 50).

-Difference between elements, compound, mixtures, atoms and molecules.

  • Element –An element is a substance that is made entirely from one type of atom. For example, the element hydrogen is made from atoms containing a single proton and a single electron. If you change the number of protons an atom has, you change the type of element it is.
  • Compound – A compound is a molecule that contains at least two different elements. All compounds are molecules but not all molecules are compounds.
  • Mixture – A compound is a molecule that contains at least two different elements. All compounds are molecules but not all molecules are compounds.
  • Atom – Atoms are the basic building blocks of ordinary matter. Atoms can join together to form molecules, which in turn form most of the objects around you.

Atoms are composed of particles called protons, electrons and neutrons. Protons carry a positive electrical charge, electrons carry a negative electrical charge and neutrons carry no electrical charge at all. The protons and neutrons cluster together in the central part of the atom, called the nucleus, and the electrons 'orbit' the nucleus. A particular atom will have the same number of protons and electrons and most atoms have at least as many neutrons as protons.

  • Molecules –A molecule is formed when two or more atoms join together chemically.
  • Isotopes –Atoms that have the same number of protons but different numbers of neutrons are called isotopes. The element hydrogen, for example, has three commonly known isotopes: protium (contains 1 proton), deuterium (contains 1 proton and 1 neutron) and tritium (contains 1 proton and 2 neutrons).

-Which theory describes the origin of the universe (Big Bang)

  • The theory that describes the origin of the universe is the Big Bang Theory.
  • The Big Bang Theory suggests that 13.7 billion years ago the universe used to be a large and very dense hot mass. According to this theory and with some proof from the Hubble Space Telescope the universe is always expanding and getting larger and larger. The universe started when that hot dense mass exploded using nuclear fission, at the start there were large amounts of energy and heat everywhere and after time passed the universe became cooler as it expanded. Slowly tiny particles combined to form some elements and planets formed.

-Precipitation reactions

  • Chemical reactions in which precipitates are formed – A precipitation reaction is a reaction in which soluble ions in separate solutions are mixed together to form an insoluble compound that settles out of solution as a solid. That insoluble compound is called a precipitate.

-Reagents, products:

  • A reagent is a chemical substance that is used to create a reaction in combination with some other substance. For example, Small Particle Reagent (SPR), a suspension of molybdenedisulfide powder in a detergent solution, is used for fingerprint detection on wet, oily, or dirty surfaces which may be unsuitable for other methods. The powder particles cling to the lipids in a fingerprint, thus rendering the fingerprint visible. Grey prints appear that can then be lifted from the surface with tape.

-Theory of plate tectonics

  • According to the theory of plate tectonics Pangaea spilt into two continents because of the earths 30 plates moving away from each other. Over many years the plates slowly drifted towards, away and past each other to form all the current day land masses.
  • Evidence for Plate Tectonics

The fact that most of the continents look like a large puzzle and could fit together.

Along the coasts of continents that were thought to have been linked Fossils found were very similar.

There are a lot of volcanos and earthquakes along the plate boundaries.

There are mountain ranges being formed where two boundaries are being pushed together, such as the Himalayas

Underwater ridges are formed where boundaries separate

Using current technology scientists can use GPS to monitor exactly how fast the plates are moving. And in which direction that each plate moves, which can help predict earthquakes and other natural disasters.

-What happens at plate boundaries

  • There are a lot of volcanos and earthquakes along the plate boundaries.
  • There are mountain ranges being formed where two boundaries are being pushed together, such as the Himalayas
  • Underwater ridges are formed where boundaries separate

-Natural disasters – impact of earthquakes

-What causes plate movements

  • The plate movements are caused by the magma under the plates continuously moving around which cause the plates to move towards or away from each other.

-Layers of the earth –

-Dawin’s theory, survival of the fittest, natural selection

-What causes earthquakes –

  • convection currents in asthnenosphere cause earthquakes

-OHM’s Law: Relationship between voltage, current and resistance.

  • V = IR (Voltage = current x resistance)

-Experimental design: variables, controls, tables, graphing

  • Independent variable:Is the variable that can be changed. For example, salt is added to water to see the rise in the boiling point of water. The amount of salt added to water is the independent variable.
  • Dependent variable: Depends on the independent variable.For example, the boiling point of water depends on the amount of salt added to water.
  • Experimental Control: Is the controlled variable, to which the results are compared. For example, the boiling point of water without anything added to it.

-Fossil evidence supporting the theory of evolution

  • Fossil evidence indicates that over time organisms of increasing complexity appeared on the earth. Bacteria and blue-green bacteria are the first fossils that were preserved from the Precambrian era.

-Fossil formation, fossil dating

There are two different types of absolute dating:

Radiocarbon Dating – This gives the ages of organic materials, it does this by measuring the radioactive decay. Carbon-14 has a half live of 5730 years and by calculating how much carbon is left the age of the sample can be determined.

Potassium-Argon Dating – For Older specimens this technique is used because the half live of Potassium-40 is much longer than carbon. Also Radiocarbon dating can only be done on organic materials, so rocks and minerals could not be dated. The Potassium-40 in the rock slowly decays into Argon-40 which gets trapped in the rock, when the rock is heated the argon escapes and the amount of gas that escapes is measured to find out the age.

Relative dating was used before the technology of absolute dating was developed. It involved estimating the age of a rock of fossil by its position in bands of rocks. This type of dating is used to determine the order in which events happened, not the date when they occurred.

-Rock types: sedimentary, igneous, metamorphic

  • Sedimentary – In most places on the surface, the igneous rocks which make up the majority of the crust are covered by a thin veneer of loose sediment, and the rock which is made as layers of this debris get compacted and cemented together. Sedimentary rocks are called secondary, because they are often the result of the accumulation of small pieces broken off of pre-existing rocks. There are three main types of sedimentary rocks:

Clastic: your basic sedimentary rock. Clastic sedimentary rocks are accumulations of clasts: little pieces of broken up rock which have piled up and been "lithified" by compaction and cementation.

Chemical: many of these form when standing water evaporates, leaving dissolved minerals behind. These are very common in arid lands, where seasonal "playa lakes" occur in closed depressions. Thick deposits of salt and gypsum can form due to repeated flooding and evaporation over long periods of time.

Organic: any accumulation of sedimentary debris caused by organic processes. Many animals use calcium for shells, bones, and teeth. These bits of calcium can pile up on the seafloor and accumulate into a thick enough layers to form an "organic" sedimentary rock.

A good example of sedimentary rocks is conglomerate.

  • Igneous–Igneous rocks are crystalline solids which form directly from the cooling of magma. This is an exothermic process (it loses heat) and involves a phase change from the liquid to the solid state. The earth is made of igneous rock - at least at the surface where our planet is exposed to the coldness of space. Igneous rocks are given names based upon two things: composition (what they are made of) and texture (how big the crystals are).

A good example of Igneous rocks is Basalt and granite

  • Metamorphic–The metamorphics get their name from "meta" (change) and "morph" (form). Any rock can become a metamorphic rock. All that is required is for the rock to be moved into an environment in which the minerals which make up the rock become unstable and out of equilibrium with the new environmental conditions. In most cases, this involves burial which leads to a rise in temperature and pressure. The metamorphic changes in the minerals always move in a direction designed to restore equilibrium. Common metamorphic rocks include slate, schist, gneiss, and marble.

Good examples of Metamorphic rocks are: Marble, Quartzite, Gneiss, Schist and Slate

-Why we use simple machines

  • so we can do work easier, eg. Using a lever and pully, wheels, ramps, screws, pivot and fulcrum

-Parts of the periodic table where active metals, normal metals, non-metals, non-active elements etc… are.

(PLEASE CHECK PEROIDIC TABLE ON NEXT PAGE)

-Where Metalloids are, i.e. (between metals and non-metals, have both metal and non metal properties)

-Name the only 2 elements to be liquid at room temperature

Mercury - Metal

Bromine – Non-metal

-What does the atomic number of an atom tell us?

-The atomic number of an atom tells us how many protons there are in the atom. The number of protons is also equal to the number of electrons in the atom.

-What does the atomic mass of an element tell us?

The atomic mass of an element tells us the Protons + Neutrons in the element.

The number of neutrons can be worked out by Subtracting Atomic No. from Atomic Mass.

-Series and parallel circuits, difference between them

  • A Series circuit is a circuit where if one light globe (resistor) short circuits or stops working all of them will stop working. Below is an example of a series circuit –
  • A parallel circuit is where each light globe (resistor) has the current flowing through it from the main switch. If one light globe (resistor) stops working the rest of the light globes will continue to work. Below is an example of a Parallel circuit –

-How are the properties of elements in the periodic table predicted?

They are predicted by the group they are in

-Life cycle of a star – (Protostars)

Stars start off as dense clouds called giant modular clouds (GMCs) with millions of particles very close together, the clouds can get triggered into compressing with a gravitational collapse. It turns into a protostar as it produces heat and collapses. Some protostars do not reach a high enough temperature to create a large planet and scientists have named them Brown Dwarfs. If the star is hot enough then it starts nuclear fusion and becomes a stable star. The mass of the star determines the colour and temperature. After millions years, depending the size of the star all the hydrogen needed for nuclear fusion is depleted, the star collapses and helium fusion begins which causes the star to expand greatly. If the star is not large enough to create enough heat to star helium fusion then a Red Dwarf is formed, which after trillions of years turns into a White Dwarf. Super Massive Stars have expanded into Gigantic Red Supergiants the core pulls the outer layers inwards making the star smaller, hotter and denser the elements begin to fuse into other heavier elements. When iron begins to be formed energy stops being released and starts being absorbed, at this point the star collapses and sends out shockwaves though space as a supernova.

The following diagram shows the life cycle of a star:

-Symbols on bottles

X on a bottle means it is an explosive

Flame on a bottle means it is flammable

Skull on a bottle means it is poisonous

(for the trial exam the last picture/left over means it is corrosive)

-Experimental inference

  • An educated guess about an experiment result. Like a hypothesis.

-Different reaction types

  • acid plus metal produces salt plus hydrogen gas
  • acid plus metal hydroxide produces salt and water
  • acid plus metal oxide also produces salt and water
  • acid plus metal carbonate produces salt, carbon dioxide gas and water
  • acid plus metal hydrogen carbonate also produces salt, carbon dioxide gas and water
  • acid plus metal sulfate produces salt, sulfur dioxide gas and water.
  • A combustion reaction is when oxygen combines with another compound to form water and carbon dioxide. These reactions are exothermic, meaning they produce heat. An example of this kind of reaction is the burning of napthalene:

C10H8 + 12 O2 ---> 10 CO2 + 4 H2O

  • Decomposition: A decomposition reaction is the opposite of a synthesis reaction - a complex molecule breaks down to make simpler ones. These reactions come in the general form:

AB ---> A + B

One example of a decomposition reaction is the electrolysis of water to make oxygen and hydrogen gas:

2 H2O ---> 2 H2 + O2

Corrosion

  • Corrosion is the primary means by which metals deteriorate. Most metals corrode on contact with water (and moisture in the air), acids, bases, salts, oils, aggressive metal polishes, and other solid and liquid chemicals. Metals will also corrode when exposed to gaseous materials like acid vapors, formaldehyde gas, ammonia gas, and sulfur containing gases. Corrosion specifically refers to any process involving the deterioration or degradation of metal components. The best known case is that of the rusting of steel. Corrosion processes are usually electrochemical in nature, having the essential features of a battery.

When metal atoms are exposed to an environment containing water molecules they can give up electrons, becoming themselves positively charged ions, provided an electrical circuit can be completed. This effect can be concentrated locally to form a pit or, sometimes a crack, or it can extend across a wide area to produce general wastage.