Fig. 1.1 represents the electron arrangement of a neutral atom of element J. Each dot is one electron. (a) State the number of electrons in the outer (highe...
Question 1 Report
Fig. 1.1 represents the electron arrangement of a neutral atom of element J. Each dot is one electron.
(a) State the number of electrons in the outer (highest) energy level of atom J. [1]
(b) Use Fig. 1.1 to deduce the group of the Periodic Table to which J belongs. [1]
(c) State how many occupied electron shells J has, and hence give its period number. [2]
(d) An atom of J contains 18 neutrons. Calculate its nucleon number. [1]
Answer Details
What this tests: reading group and period from an electron diagram, and working out nucleon number.
The dots fill the shells 2, then 8, then 7 outward from the centre.
(a) The outer (third) shell holds 7 electrons [1].
(b) The number of outer-shell electrons gives the group number, so J is in Group VII [1].
(c) There are 3 occupied shells [1], and the number of occupied shells gives the period, so J is in Period 3 [1].
(d) The proton number equals the total number of electrons: \(2+8+7 = 17\). Nucleon number = protons + neutrons = \(17 + 18 = 35\) [1]. (These values identify J as chlorine.)
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