C2.3 Atomic structure etc. Flashcards Preview

Chemistry > C2.3 Atomic structure etc. > Flashcards

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

What is the mass number of an atom?

The total number of protons and neutrons


What is an isotope?

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


What symbol represents relative atomic mass?


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


What symbol represents relative formula mass?


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


What is one mole of a substance?

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


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


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


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


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

Carbon (Ar 12)


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

The proton number / atomic number