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Mid-Topic Test Revision NAME: _______________________ form: _____________ 1. Complete the following table: Name Democritus How they contributed to atomic theory Proposed that matter was made up of small, indivisible particles called atoms. (You should have 5 main points, do some research!) John Dalton Joseph J Thomson Elements are made of extremely small particles called atoms. Atoms of different elements differ in size, mass and other properties. Atoms cannot be created or destroyed – matter can simply change form. Atoms of different elements can combine to form compounds. In chemical reactions, atoms are combined, separated or rearranged. “Plum pudding” model of the atom: atoms consist of a large sphere that is positively charged, with smaller, negatively charged particles embedded throughout. Ernest Rutherford Niels Bohr Proposed a small, positively charged nucleus where most of the mass of the atom is contained. Used the gold-foil experiment to identify the nucleus in the centre of the atom. Postulated that the number of protons and electrons are equal. Proposed that electrons exist in fixed orbits surrounding the nucleus. These electron “shells” or energy levels held the electrons in orbit around the nucleus much like a planetary system. When excited, electrons can move between orbits. 2. Name the three sub-atomic particles that make up an atom. Protons, neutrons and electrons 3. Describe where each of the three subatomic particles can be found within the atom. Protons and neutrons = in the nucleus. Electrons = in shells surrounding the nucleus. 4. Define the atomic number. The atomic number is the number of protons with the nucleus of an atom. It is unique to each element. 5. Define the mass number. The mass number is the number of protons AND NEUTRONS in the nucleus of an atom. 6. Complete the table below: Element Symbol Carbon Aluminium Nitrogen Zinc Calcium Gold C Al N Zn Ca Au Atomic number 6 13 7 30 20 79 # protons # electrons 6 13 7 30 20 79 6 13 7 30 20 79 Mass number 12 27 14 65 40 197 # neutrons 6 14 7 35 20 118 7. State the maximum number of electrons that will fill in the first energy level, second energy level and third energy level of an atom. First = 2, second = 8 and third = 18. 8. A magnesium atom has the atomic number 12. Draw a diagram showing how the electrons would be arranged in this atom. 1st energy level = 2 electrons 2nd energy level = 8 electrons 3rd energy level = 2 electrons 9. Draw a diagram of a Neon atom. Neon: atomic number = 10 # protons = 10 # electrons = 10 1st shell = 2 electrons 2nd shell = 8 electrons 10. Compare the properties of metals and non-metals. METALS: shiny, ductile, malleable, conduct electricity and heat, high melting point. NON METALS: dull, brittle, do not conduct electricity or heat, lower melting point. 11. What do the terms “malleable”, “ductile” and “brittle” mean? Malleable: able to be hammered or pressed into sheets or shapes without breaking. Ductile: able to be drawn out into a thin wire. Brittle: breaks or crumbles easily. 12. Explain why we make cooking utensils such as pots and pans out of metal rather than other materials? Metal is a good conductor of heat and has a high melting point; therefore metal cookware allows us to effectively heat our food without the pan melting or becoming damaged. 13. Circle the items below which are COMPOUNDS. Underline the ELEMENTS. H H2O Cu Mg C6H12O6 14. State the difference between an atom and a molecule. A molecule is a cluster of atoms. Si CO Co