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Flashcards in atomic structure and calculations Deck (18)
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1

what is a compound

- composed of two or more elements chemically joined

2

what is an atom

- smallest parts of an element

3

what is found in the nucleus

- proton: positive charge (same number as electrons)
- neutron: neutral charge

4

what are electrons

- negative charge
- orbit the nucleus in the electron cloud
- same number of electrons as protons

5

what is the mass number

- number of protons and neutrons in the nucleus
- known as 'a'
- found at the top of the element

6

what is the atomic number

- number of protons (same as the number of electrons)
- known as 'z'
- found at the bottom of the element

7

what is an isotope

- atoms that have the same number of protons and a different number of neutrons
- resulting in a different mass number

8

what is relative atomic mass

- Ar: the average mass of one element

9

what is relative molecular mass

- Mr: average mass of a compound

10

what is percentage composition

- percentage by mass of each element in a compound
- percentage of an element = (total Ar for element / total Mr for that compound) x 100

11

what is a mole

- 6.022 x 10^23 particles of a substance (n)

12

what is molar mass

- the mass of one mole of a substance (M)
- units: g mol^-1)

13

what is an element

simplest substance (cannot be broken down)

14

what is atomic mass

-mass of one mole of atoms of an element (amu)

15

what is molecular mass

- mass of one mole of molecules of an element or compound (amu)

16

what are the three triangles used for mole calculations

- N = n x NA
- m = n x M
- V = n x Vm

17

what is molar volume

- volume occupied by one mole of gas at STP (22.71)

18

what is STP

- standard temperature ( 0*C) and pressure (100kPa)
- temperature: always answer in kelvins (k) 0*C = 273.15k
- *C + 273.15 = k
- pressure: always answer in kilo pascals (kPa) 1atm = 101.3kPa
- atm x 101.3 = kPa