C2.3 Atomic structure etc. Flashcards Preview

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Flashcards in C2.3 Atomic structure etc. Deck (10):
1

What is the mass number of an atom?

The total number of protons and neutrons

2

What is an isotope?

Isotopes are atoms of the same element that have different mass numbers but the same atomic number

3

What symbol represents relative atomic mass?

Ar

The mass of the particular ATOM
eg K, Na, Rb

4

What symbol represents relative formula mass?

Mr

The mass of the whole molecule
eg H7C13 would be 7 x Ar of H plus 13 x Ar of C

5

What is one mole of a substance?

One mole is the Mr / Ar of a substance shown in grams

6

If one mole of Carbon monoxide is 28g, how many moles are in

-56g of carbon monoxide
-14g of carbon monoxide

56 / 28 = 2
2 moles

14/28 = 0.5
0.5 moles

7

Why is the Ar for some elements not a whole number (eg chlorine = 35.5)?

The Ar is the average atomic mass from all the isotopes of the element

8

How would you calculate the Ar of Chlorine where 75% have an Ar of 35 and 25% have an Ar of 37?

In 100 atoms of chlorine:
75 would be 35
25 would be 37

Find the mean average:
75 x 35 = 2625
25 x 37 = 925
2625 + 925 = 3550
3550 / 100 = 35.5

9

What is the 'standard atom' that other atoms are relative to?

Carbon (Ar 12)

10

What part of the element stays the same in its isotopes?

The proton number / atomic number