Unit 1 Atomic Structure and Properties
1 Moles and Molar Mass
chemists use moles to connect the mass of substances reacting
and the number of particles undergoing chemical changes
1Mole 6 022 1023particles Avigadro's number
Molar mass is used to convert quantities between mass units
grams and count units moles
1 mole molar mass g
ex Imole Na 22.9dg Na
A conversion factor is a ratio which represents the relationship between the
same quantity in to different units
2 Mass Spectroscopy of Elements
9 1 70 2 72 3 73 74 4 76 1
2 11 21.6 7 3 29.2 7.6
3 80.1 80
4 Mercury
Mass spec is a technique used to identify the isotopes
of an element and their relative abundance in nature
steps
Multiply each isotope by its relative abundance
Add the results
, Round to two sigfigs
Identify the element
Mass number protons neutrons Protons are the isotopes
3 Elemental Composition of Pure Substances
All pure substances elements and compounds have a fixed composition
This means the elements present and the ratio of the element's
atom is the same for every sample of the compound
Ex Sodium Chloride NaCl is a 1 1 ratio
4 Composition of Mixtures
A mixture contains more than one pure substance
Mixtures have variable compositions depending on the pure substanc
they contain and the relative amount of those substances
Solutions are an example of mixtures
The elemental composition of a mixture can be used to determ
the relative amounts of pure substances that compose it
Elemental analysis finding the relative mass of one or more
elements in the mixture 7 is often used by chemists to
determine how pure a substance is
Ex: A 2.4g sample of a mixture of CaCl2, and NaCl is found to contain 0.12g Na. What percent of
this sample is NaCl
1 Determine moles of Na
0.12.9 Na Imo Na 23.0gmol 5.22.10 mol Na
1 Moles and Molar Mass
chemists use moles to connect the mass of substances reacting
and the number of particles undergoing chemical changes
1Mole 6 022 1023particles Avigadro's number
Molar mass is used to convert quantities between mass units
grams and count units moles
1 mole molar mass g
ex Imole Na 22.9dg Na
A conversion factor is a ratio which represents the relationship between the
same quantity in to different units
2 Mass Spectroscopy of Elements
9 1 70 2 72 3 73 74 4 76 1
2 11 21.6 7 3 29.2 7.6
3 80.1 80
4 Mercury
Mass spec is a technique used to identify the isotopes
of an element and their relative abundance in nature
steps
Multiply each isotope by its relative abundance
Add the results
, Round to two sigfigs
Identify the element
Mass number protons neutrons Protons are the isotopes
3 Elemental Composition of Pure Substances
All pure substances elements and compounds have a fixed composition
This means the elements present and the ratio of the element's
atom is the same for every sample of the compound
Ex Sodium Chloride NaCl is a 1 1 ratio
4 Composition of Mixtures
A mixture contains more than one pure substance
Mixtures have variable compositions depending on the pure substanc
they contain and the relative amount of those substances
Solutions are an example of mixtures
The elemental composition of a mixture can be used to determ
the relative amounts of pure substances that compose it
Elemental analysis finding the relative mass of one or more
elements in the mixture 7 is often used by chemists to
determine how pure a substance is
Ex: A 2.4g sample of a mixture of CaCl2, and NaCl is found to contain 0.12g Na. What percent of
this sample is NaCl
1 Determine moles of Na
0.12.9 Na Imo Na 23.0gmol 5.22.10 mol Na
