Everything on Earth is made up of matter, that is, of elements and of the compounds they form. Matter is everything that you can touch/see/feel or smell
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- EXERCISES: 1. What am I Choose from: electron, ion, neutron, nucleus, proton.
- 2. Use how, how many, what, which to complete the questions.
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UNIT 1 TEXT Everything on Earth is made up of matter, that is, of elements and of the compounds they form. Matter is everything that you can touch/see/feel or smell. Chemistry is the study of matter and the changes that take place within that matter. There are three main states of matter: solids, liquids and gases. Each of these states is also known as a phase. A solid is matter with a rigid shape and a fixed volume that does not change much with temperature. A liquid has a fixed volume but not a fixed shape and it takes the shape of its container. Its volume may alter with changes in temperature and pressure. A gas has neither fixed volume nor shape, as it expands to fill its container completely. Its volume is very sensitive to temperature and pressure. Matter is composed of different kinds of atoms. An atom is made up of electrons, protons and neutrons. Protons and neutrons are in the nucleus, the centre of the atom. Electrons spin very quickly around the nucleus. Electrons have a negative charge, protons have a positive charge and neutrons have no charge. The number of protons always equals the number of electrons in an atom, so the atom is neutral. If some electrons are added or removed, the atom becomes 7 charged and is then an ion. A molecule is a particle containing two or more atoms chemically bonded together. Matter has physical and chemical properties. Physical properties include density, melting point, boiling point, freezing point, colour or smell. An example of chemical properties is the way elements combine with each other in reactions. An element is matter that consists of only one kind of atom. A compound is a substance consisting of two or more chemically bonded elements, with a fixed ratio determining the composition. Elements and compounds can move from one phase to another when special physical forces are present. One example of those forces is temperature. When temperature changes, the phase can change. You can see water vapour over a boiling pot of water. That vapour (or gas) can condense and become a drop of water. If you put that drop in the freezer, it becomes a solid. No matter what phase it is in, it is still water. It still has the same chemical properties. QUESTIONS: 1. Why do you think it is important to study chemistry? 2. What is METTER? 3. What is electrons? 4. What is protons? EXERCISES: 1. What am I? Choose from: electron, ion, neutron, nucleus, proton. a. I’m the centre of the atom, I contain protons and neutrons. I’m the ... b. I move around the nucleus. I’m an ... c. I’m positively charged. I’m a ... d. I’ve no charge. I’m a ... 8 e. I’m an electrically charged atom. I’m an ... 2. Use how, how many, what, which to complete the questions. a. ... is matter? b. ... can matter exist? c. ... of the three states of matter have a fixed shape? d. ... of them have no fixed volume? e. ... are atoms made up of? f. ... of the constituents of an atom are outside the nucleus? g. ... are the properties of matter classified? h. ... kinds of atoms are there in an element?
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