ScienceSolutionsSeries 1 / Item: 2
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Answers
1(a)The closer together particles are, (atoms) the more solid they become. Therefore particles which are far apart would be a gas.
2(b)The centre or nucleus of atoms contains the protons and neutrons, while the remaining electrons are to be found travelling in the outer regions of the atom.
3(b)Heat applied to a material causes the atoms to absorb energy from the heat source. This additional energy causes the atoms to move faster and further apart. The more heat applied, the faster and further the atoms move.
4(b)The diagrams depict the way atoms behave in various states. Matter is made up of atoms. Atoms in a solid (A), are packed tightly together, and cannot move freely. In a gas there is a great deal of space between the particles so they can move around freely. This is why gases can be compressed.
5(c)The periodic table took almost a century to evolve. It displays the properties of the element. The table was mainly put together by a Russian scientist called Dimitri Mendeleev in the early 1800’s.
6(a)Elements can be mixed together to form mixtures. Mixtures can be separated, in the case of iron and copper, by using a magnet. The iron is attracted by the magnet, while the copper is not.
7(b)Evaporation, like boiling, involves a change form a liquid phase to a gas phase. This process occurs at any temperature (the temperature depends on the substance), not only at 100oC, the boiling point of water at sea level. When a substance boils, it has more energy; this increase in energy causes the atoms to move faster. This, in turn, allows the atoms to ‘escape’ into the surroundings.
8(c)Mass number increases as you go from left to right of the periodic table. There are also other trends from left to right such as: elements change from metals to semi-metals to non-metals.
9(b)If an atom gains electrons it is known as a negative ion, as the electrons gained have a negative charge. Conversely, if atoms lose electrons the atom becomes a positive ion, as the overall charge is now positive.
10(b)If a pure substance is made up of one type of atom, it is an element. When two or more different atoms are joined in a fixed way, it is known as a compound. An example of a compound is water, which is made up of two hydrogen and one oxygen atoms chemically combined together.
True / False
1False
Intermolecular forces are the forces which try to keep atoms in a substance together. As atoms in a gas are spread further apart as compared to a solid, it would suggest the intermolecular forces acting on the solid must be stronger, as the atoms are held tightly together.
2True
Hot gas has more heat and therefore energy. The higher energy in the hot gas causes the atoms to move faster and further, and have more chance of colliding. When they collide at a higher speed they ‘bounce’ further apart, therefore they require a greater space (less dense).
3True
The periodic table displays approximately 90 elements that occur naturally. Scientists have been able to make a further 25 or so new elements. An example of a made element is Neodymium (symbol Nd).
4False
In 1968 scientists discovered other particles within the nucleus, which they called quarks. Each proton contains three quarks which are held together by other particles called gluons. Neutrons also contain quarks.
5True
Electrons are minute in comparison with protons and neutrons; the size difference is x1836. The size is so small; it is not taken into consideration when measuring the mass of atoms.
6False
B, C and D represent a compound. Don’t forget; a molecule of an element has one type of atom whereas a molecule of a compound consists of two or more different types of elements.
7False
The spaces between gas particles are greater because gas atoms have more energy therefore move greater distances, collide more often and hence tend to have more spaces between them.
8True False
Gas particles move freely in all directions to occupy any available space. It would therefore take up all the available space within the container.
Liquid Solid Gas
9True
Matter can be living or non-living, and can be in any place. Unless matter gets to an extremely high temperature such as with some stars, or a hydrogen bomb explosion, it will always exist in one of three of these states.
10True
A water molecule, which is a compound, consists of two hydrogen and one oxygen atoms. H2O can be split by using a Hoffman or hydrogen voltammeter. This device passes an electrical current through the water, which causes the water to separate into hydrogen and oxygen gas.
Match the Word to the Statement
1E - Diffusion
A room air freshener is sprayed; the smell spreads throughout the room. This is due to a process called?
2H - Sub-atomic particles
Positrons, quarks, neutrinons and bosons represent?
3G - Electron
This particle is negatively charged?
4D - Proton number
Elements are arranged in the order of increasing …………….. in the periodic table?
5C - Cation
Na+ is a positively charged atom, and is called a?
6A - Chemical formula
From this, the number and kind of atoms can be inferred?
7F - Chemical symbol
This represents an atom of an element in the periodic table?
8B - Motion
Changes in the state of matter are due to the change in ……….. of the atoms?
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