An element is represented by symbol 20
40
(i) What is the mass number and atomic number of element X?
(ii) Name its valence shell and number of electrons in the valence shell
(iii) Is the element a metal or a non metal
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Answers
Answer:
Mass Number(A) = Number of Protons + Number of Neutrons
An isotope of any element can be uniquely represented as AZX, where X is the atomic symbol of the element, A is the mass number and Z is the atomic number. The isotope of carbon that has 6 neutrons is therefore 126C.
As a general rule, a main group element (except hydrogen or helium) tends to react to form a s2p6 electron configuration. This tendency is called the octet rule, because each bonded atom has 8 valence electrons including shared electrons.
The elements can be classified as metals, nonmetals, or metalloids. Metals are good conductors of heat and electricity, and are malleable (they can be hammered into sheets) and ductile (they can be drawn into wire).
Explanation:
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