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The diagram shows the first twenty elements in their positions in the periodic table - Junior Cycle Science - Question (b) - 2008

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Question (b)

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The diagram shows the first twenty elements in their positions in the periodic table. The number given with each element is the atomic number of that element. (i) D... show full transcript

Worked Solution & Example Answer:The diagram shows the first twenty elements in their positions in the periodic table - Junior Cycle Science - Question (b) - 2008

Step 1

Define atomic number.

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Answer

The atomic number is defined as the number of protons in the nucleus of an atom. It also equals the number of electrons in a neutral atom, which balances the positive charge of protons.

Step 2

Explain the underlined term.

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Answer

Isotopes are variants of the same chemical element that have the same number of protons (and thus the same atomic number), but different numbers of neutrons. This results in different mass numbers for isotopes of the same element. For example, lithium has two naturally occurring isotopes: lithium-6 and lithium-7, which differ in their neutron counts.

Step 3

By what name are group two metals known?

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Answer

Group two metals are known as alkaline earth metals. They are characterized by their shiny appearance and low density.

Step 4

Why are the noble gases, group 8/0, very chemically unreactive?

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Answer

Noble gases, such as helium, neon, and argon, are very chemically unreactive due to their stable electronic configuration. They have a full outer orbit (shell) with eight electrons, which makes them energetically stable and less likely to form chemical bonds with other elements.

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