Atoms and amount of susbtance

Question 1

Charges on subatomic particles

Answer 1

proton - positive charge
neutron - neutral
electron - negative charge

charge on proton is equal but opposite to electron charge

Question 2

masses of subatomic particles

Answer 2

proton - 1
neutron - 1
electron 1/1840 (negligible)

Question 3

isotope

Answer 3

atoms of the same element with different number of neutrons so different masses

Question 4

isotopes and chemical reactions

Answer 4

different isotopes of same element have same number of electrons
number of neutrons has no effect on reactions
therefore isotopes react in the same way

Question 5

ion

Answer 5

charged atom with different number of electrons to protons

Question 6

relativic atomic mass

Answer 6

weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12

Question 7

mole

Answer 7

amount of substance that contains 6.02 x 10^(23) particles (avogadro constant - number of particles in a mole of carbon 12)

Question 8

molar mass

Answer 8

mass in grams in each mole of a substance

Question 9

molecular formula

Answer 9

number of atoms of each element in a molecule

Question 10

empirical formula

Answer 10

simplest whole number ratio of atoms of each element in a compound

Question 11

ideal gas equation

Answer 11

pv=nRT
P in Pa so 1kpa = 1000pa so x1000
T in K so 1C = 273K so +273
V is in m3 1cm3 = 0.000001 x10-(^6)

Question 12

What is molecular ion peak?

Answer 12

• mass of whole molecule in sample that hasn’t been fragmented
• usually an extremely small percentage with w higher mass than the rest

Question 13

What is the M+1 peak?

Answer 13

• Higher mass by one that ‘molecular ion peak’ due to the isotope of an atom in molecule

Question 14

What are the uses of mass spectrometry?

Answer 14

• identifies unknown compounds
• determines the abundance of isotopes in an element
• more knowledge about structure and chemical properties of molecules

Question 15

Why might percentage yield be less than 100% (4)

Answer 15

Reaction might not be complete

Other unwanted reactions happen

Product lost in purification

Starting material may be impure