Module 3 - periodic table and energy

Question 1

How are elements aranged in the periodic table?

Answer 1

proton number

Question 2

What are the names of groups 1 2 7 and 8?
What is the name of the elements in the middle of the periodic table?

Answer 2

Alkali metals Alkaline earth metals Halogens Noble Gasses
Transition metals

Question 3

Which elements exist as diatomic molecules?

Answer 3

H2 N2 O2 Halogens: F2 Cl2 Br2 I2
Have No Fear Of Ice Cold Beer

Question 4

Why do noble gasses have the lowest melting point?

Answer 4

Exist as single atoms

Question 5

Define metallic bonding

Answer 5

Electrostatic attraction between metal cations and delocalised electrons from the outer shell

Question 6

Why do melting points increase across the period?

Answer 6

More delocalised electrons
Charges of cations increase
smaller ion = higher charge density:ratio of charge to volume

Question 7

Define giant covalent structure and their properties

Answer 7

Network of covalently bonded atoms
High melting points

Question 8

Define allotrope

Answer 8

pure forms of the same element that differ in structure

Question 9

Group 2 reacts with water to produce …

Answer 9

hydroxides and hydrogen gas

Question 10

Group 2 reacts with diluted acids to produce …

Answer 10

salts and hydrogen

Question 11

They burn in oxygen with what characteristic colour?

Answer 11

Brick red

Question 12

What is the test for Ba 2+ ions?

Answer 12

White pricipitate forms

Question 13

What are the periodic trends of alkaline earth metals?

Answer 13

Atomic and ionic radius increases down group - more shells
Ionisation energy decreases down group
Reactivity increases down group
Melting points decrease down group
Solubility of oxides and hydroxides increase down group

Question 14

What is the trend in the halogen group?

Answer 14

Less electronegative down group
Less reactive down group
Melting point/boiling point increase down group
Larger molecules
more electrons
stronger london forces

Question 15

What are some disadvantages of water treatement with chlorine?

Answer 15

Cl2 harmful and toxic - irritates respiritory system:liquid chlorine burns eyes/skin
Cl2 reacts with organic compounds to form chlorinated hydrocarbons- carcinogenic

Question 16

What are some alternitives to treating water with chlorine?

Answer 16

ozone
Uv light

Question 17

What are the tests for all the halides

Answer 17

F- no precipate doesn’t dissolve
Cl- White precipitate dissolves in diluted NH3
Br- crem precipitate dissolves in concentated NH3
I- yellow precipitate insoluble

Question 18

How to identify halide ions in displacement reactions

Answer 18

F2 yellow gas
Cl2 green gas water-colourless hexane-pale green
Br2 red brown liquid water-yellow/orange hexane-orange/red
I2 black purple solid water-brown hexane-pink/purple

Question 19

What is the test for carbonates?

Answer 19

Fizzing carbonate dissapears

Question 20

What is the test for CO2?

Answer 20

lime water turns cloudy

Question 21

What is the test for sulphate?

Answer 21

white precipitate

Question 22

What is the test for ammonium?

Answer 22

litmus paper turns from red to blue

Question 23

What are some common insoluble salts?

Answer 23

silver halides
barium sulfate
most carbonates - except sodium potassium and ammonium carbonates
metal oxides

Question 24

What are some common soluble salts?

Answer 24

most hydrogen carbonates
most sodium salts

Question 25

what are the standard conditions for enthalpy change?

Answer 25

100 kPa 298 K

Question 26

Define standard enthalpy change of reaction

Answer 26

the enthalpy change when the reaction occurs in the molar quantities shown in the chemical equation under standard conditions in their standard states

Question 27

Define enthalpy change of formation

Answer 27

enthalpy change when 1 mol of a compound is formed from its elements in their standard states under standard conditions

Question 28

Define enthalpy change of combustion

Answer 28

the enthalpy change when 1 mole of a substance is completely burned in oxygen under standard conditions, all reactions and products being in their standard states

Question 29

Define enthalpy change of neutralisation

Answer 29

the enthalpy change when 1 mole of water is formed from the neutralisation of hydrogen ions by hydroxide ions under standard conditions

Question 30

What is the equation for bond enthalpy?

Answer 30

sum of bonds broken - sum of bonds formed

Question 31

Define bond dissociation enthalpy

Answer 31

bond dissosiation enthalpy per mole of gaseous compound

Question 32

Define average bond enthalpy

Answer 32

energy needed to break one mole of bonds in the gas phase averaged over many different compounds This value is ALWAYS positive

Question 33

Bond forming ... energy Bond breaking ... energy

Answer 33

Releases Requires

Question 34

Define activation energy

Answer 34

Minimum amound of energy needed to begin breaking reactant bonds and start a chemical reaction ALWAYS POSITIVE

Question 35

Which way do arrows point in exo and endothermic reactions?

Answer 35

Exothermic down Endothermic up

Question 36

What is the equation for enthalpy change?

Answer 36

q=mcdeltaT q=enthalpy change m=mass of water c=4.18 deltaT=change in temp

Question 37

What are some reasons for underestimation of enthalpy change?

Answer 37

Heat absorbed by container and lost to surroundings Incomplete combustion Non standard conditions

Question 38

Define Hess law

Answer 38

The total enthalpy change for a reaction is independant of the route taken (as long as initial and final conditions are the same)

Question 39

What are some factors that impact the rate of a reaction?

Answer 39

temperature surface area catalyst concentration of reactants pressure of gasses

Question 40

What are some methods of measuring rate of reaction

Answer 40

precipitation change in mass volume of gas titration

Question 41

what is the equation for rate of reaction?

Answer 41

difference in concentration/difference in time

Question 42

How do you calculate the gradient of a linear graph?

Answer 42

change in Y/change in X

Question 43

Define catalyst

Answer 43

Increases rate of reaction by lowering activation energy and providing an alternative reaction pathway. Catalysts are not used up during the reaction (unchanged)

Question 44

What is a homogenous catalyst?

Answer 44

same physical state of reactants, forms intermediates

Question 45

what is a hetrogenous catalyst?

Answer 45

different physical state to reactant

Question 46

What is a dynamic equalibrium?

Answer 46

rates of the foreward and reverse reactions are equal concentrations of reactants and products remain constant only in closed systems

Question 47

Define Le Chetalliers principle

Answer 47

When the conditions of a system at equalibrium change, the position of the equalibrium shifts in the direction that opposes the change

Question 48

How is equalibrium affected by an increase in pressure?

Answer 48

Shifts to the side with fewer moles

Question 49

What is the equalibrium equation?

Answer 49

aA + bB - cC + dD double arrows

Question 50

What is equalibrium law?

Answer 50

Kc= (C)c (D)d (A)a (B)b Brackets concentration

Question 51

What is Kc dependant on?

Answer 51

Temperature