atomic structure & periodic table

Question 1

relative atomic mass (A subscript r) definition

Answer 1

-the weighted mean of the mass numbers of the isotopes of an element, taking into account the abundances of the various isotopes of the element

Question 2

general formula for calculating Ar

Answer 2

(% x mass no. of isotope A) + (% x mass no. of isotope B)…

Question 3

Mr(subscript r) =

Answer 3

the gfm

Question 4

first 20 elements of the periodic table

Answer 4

1. H, He
2. Li, Be, B, C, N, O, F, Ne
3. Na, Mg, Al, Si, P, S, Cl, Ar
4. K, Ca

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Question 5

group vs period number

Answer 5

• group number of the element = no. of electrons in the outer shell
• period number of the element = no. of electron shells

Question 6

group names

Answer 6

group 1: alkali metals
group 2: alkali earth metals
group 7: halogens
group 8/0: noble gases

Question 7

isotopes

Answer 7

• same atomic number, different mass numbers

- isotopes of the same element have the same chemical properties