Atom, Elements And Molecules

Question 1

Define atom

Answer 1

A smallest unit of an element that still has the properties of an element

Question 2

Define element

Answer 2

A substance that is made up of only one type of atom

Question 3

Define ion

Answer 3

An atom or a group of atoms that have positive or negative charge

Question 4

Define molecule

Answer 4

A group of atoms that are chemically bonded together

Question 5

Define compound

Answer 5

A group of atoms that consists of two or more types of atoms bonded together

Question 6

Define empirical formula

Answer 6

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

Question 7

Define molecular formula

Answer 7

The actual number of atoms of each element present in a compound

Question 8

Define mole

Answer 8

The amount of any substance containing the same number of particles asa there are atoms in exactly 12g of carbon-12

Question 9

Define the avogadro constant

Answer 9

The number of particles in one mole of a substance . This is 6.02x10^23 particles

Question 10

Equation of avogadros constant to moles

Answer 10

Number of particles = moles x avogadro constant

Question 11

Define relative atomic mass

Answer 11

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

Question 12

Define relative formula mass

Answer 12

The sum of the relative atomic masses of atom in a formula unit

Question 13

Define relative molecular mass

Answer 13

The sum of the relative atomic masses of atom on a molecule

Question 14

Define ppm

Answer 14

Parts per million

The ratio of one gas to another

Question 15

Define concentration

Answer 15

Is the amount of solute dissolved per dm^3 of solution

Question 16

How can concentration be calculated in g dm^3

Answer 16

Concentration (g dm^3) = mass(g) / volume (dm^3)

Question 17

Concentration be calculated mol dm^3

Answer 17

Concentration = moles / volume (dm^3)

Question 18

Calculate number of moles of a goven substance using the mass and molecular mass

Answer 18

Number of moles = mass/ relative molecular mass

Question 19

What the equation links molar volume at RTP and moles

Answer 19

Volume of gas at RTP (dm^3) = moles x 24

Question 20

Ideal gas law

Answer 20

PV = nRT

P-pressure (pascal)
V - volume (m^3)
n ( moles)
R- gas constant (8.31 J K mol^-1)
T temperature ( kelvin)

Question 21

How can percentage yield be calculated

Answer 21

Percentage yield = (actual yield) divide theoretical yield) x 100

Question 22

Why might the actual yield of product be less than expected

Answer 22

• incomplete reaction
• unwanted side reactions
• practical losses

Question 23

What is atom economy of a reaction

Answer 23

Atom economy is a measure of the efficiencyof the reaction. It looks at the amount of reactant that get turned into useful products

Question 24

How can atom economy be calculated

Answer 24

Atom economy = (molar mass of desired product) divide (total molar mass of products) x 100

Question 25

The ____ the atom economy, the more sustainable and efficient the process

Answer 25

Higher

Question 26

What are displacement receaction