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Questions on unit 1 Lesson 3 I. Complete the following statements: 1. The smallest part of the element that takes apart in a chemical reaction is known as atom 3. The symbol of carbon atom is C while that of calcium atom is Ca 4. The symbol of nitrogen atom is N while that of neon atom is Ne 5- Na is the symbol of sodium atom, while that of sulphur atom is S 7. The nucleus of the atom contains two different types of particles, these are protons and neutrons 8. The atom consists of nucleus and electrons 9. In the nucleus, there are positively charged particles called protons and neutral particles called neutrons 10. The mass of the atom is concentrated in the nucleus because the mass of electron is negligible if it is compared to the mass of Protons or neutrons. 11. Electrons have negative charge, while protons have positive charge. 12. Electrons revolve around the nucleus in energy levels ,where each one of them has its own energy 13. The number of neutrons in the nucleus of an atom may be equal to or greater than the number of protons 14. The atom is electrically neutral because the number of protons in the nucleus is equal to the number of electrons 15. The sum of the numbers of the protons . and neutrons in the nucleus is known as mass number II. Write the scientific term for each of the following: 1. The fundamental building unit of matter that can take apart in the chemical Reaction. atom 2. The positively charged particle in the nucleus of an atom. protons 3. The number of positively protons in the nucleus. Atomic number 4. Neutral particle exists in the nucleus of an atom. Neutrons 5. Negatively charged particles of negligible mass that revolves around the nucleus. Electrons 6. A part of an atom exists in its center. Nucleus 7. The number which is written at the bottom left side of the element symbol. Atomic number 8. The number which is written at the top left side of the element symbol. Mass number 9. The difference between the mass number and the atomic number. Number of neutrons 10. The sum of the numbers of protons and neutrons in the nucleus. Mass number III. Put (√) in front of the right statement and (x) in front of the wrong one and correct it : 1. The molecule is the smallest part of the element that can take apart in the chemical reaction without changing. (X) The atom 2. (He) is the symbol of hydrogen element, while (H) is the symbol of helium element. ( X ) ( H ) ( He ) 3. The symbol of zinc is (Zn), while (Si) is the symbol of sulphur. ( X) (S) 4. (Fe) is the symbol of iron. 5. The atom is electrically charged, while its nucleus is electrically neutral. ( X) Neutral – positively charged IV. Give reason for:1. the atom is electrically neutral. - Because the number of positive protons equal number of electrons . 2. the mass of the atom is concentrated in the nucleus. - Because the mass of electrons is negligible relative to the mass of protons and neutrons 3. the electrons are distributed to fill the (K) level before filling the (L)level. - Because the k level has lower energy than L level 4. hydrogen molecule is diatomic, while helium molecule is mono-atomic. - Because hydrogen consists of 2 atoms while helium consists of 1 atom 5. noble (inert)gases molecule are mono-atomic. - Because inert gases consist of 1 atom V. Write the name of the elements of the following symbols: 1. H 8.K 2.He 9.Na See p.24 5 .Cl 10. Cu 11.Br VI. Write the electronic configuration of the following: , Electronic config. In H K He K F K L Ne k L Na K L M , 1 2 2 7 2 8 2 8 1 , , Then find: 1- Number of electrons in the outer level. H=1, He=2, F=7, Ne=8, Na=1 2- The number of neutrons in each atom. H=1-1=0,He4-2=2, F=18-9=9, Ne=20-10=10, Na=2311=12 3- the atomic number H =1,He=2, F=9, Ne=10, Na=11 4- the mass number H=1, He=4, F18, Ne=20, Na=23 5- Are those elements active or not. H, F, Na are active the rest are inactive VII. Write the symbols of the following element: 1) Sodium 2) Potassium 3) Chlorine Na K Cl 4) Nitrogen N 5) Calcium Ca 6) Aluminum Al 7) Phosphorus P