August 2019 NY Regents Chemistry Exam
6 As the elements in Period 2 are considered in order from lithium to fluorine, there is an increase in the (1) atomic radius (2) electronegativity (3) number of electron shells (4) number of electrons in the first shell
Solution: Going from lithium to fluorine on the Periodic table means we are going from left to right. Atomic radius decreases going from left to right.
The number of electron shells is the same for the elements in the same period.
The number of electrons in the first shell is 2 for all the elements (except H) which can be seen in electron configurations for all elements on the Periodic Table. Electronegativity increases going from left to right on the Periodic Table. Alternatively, if we do not remember the trends in atomic radius or electronegativity, we can look at Table S and compare these values for a couple of elements in Period 2.
Answer: 2
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