1.1. Chlorine has an atomic number of 17.

Figure 3 shows the arrangement of electrons in an atom of chlorine.

Figure 3

i) What is the electronic configuration of this atom?

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ii) Explain, using Figure 3, why chlorine belongs to group 7 of the periodic table.

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1.2. The nucleus of an atom is made up of protons and neutrons. Atoms of chlorine contain 17 protons.

Figure 4 shows some information about a proton, a neutron and an electron.

Figure 4

i) Explain, using the information in Figure 3 and Figure 4, why atoms of chlorine have no overall charge.

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ii) Atoms of chlorine-37 have a mass number of 37. Calculate the number of neutrons in atoms of chlorine-37.

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number of neutrons = .................................................

iii) There are two isotopes of chlorine, chlorine-35 and chlorine-37. Explain the meaning of the term isotopes.

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