C8: Non-Metals Flashcards
where are the non-metals located in the periodic table?
Elements found principally in groups V-0 of the periodic table.
non-metals have between (1) _______ and (2)______ valence electrons
(1) - 5 (2) - 8
physical properties of non-metals
- most have low melting and boiling points
- poor conductors of heat and electricity
- can be solid liquid or gas at room temperature
- weak and brittle in their solid state
- dull in appearance in their solid state
- low densities
what is an allotrope?
different forms of the same substance
non-metals will either (1)________ or (2)________ their electrons when they react.
- gain
- share
reactions between non-metals and metals are (1)__________ reactions. This is because the non-metals (2) _________ electrons from (3)______ and oxidizing it. the nonmetal itself is (4)________
- redox
- gains
- the metal
- reduced
why is the reaction between metals and non-metals considered redox reactions
electrons are transferred from the metal to non-metal, so the metal is oxidised and the non-metals reduced.
The chemical properties of non-metals are principally reactions between :
- metals
- oxygen
non-metal + oxygen ===>
- acidic oxides eg SO2, SO3, NO2, CO2
- neutral oxides eg, CO, NO, H2O
non-metals + reactive metals ====>
chlorides, oxides, nitrides, sulfides, hydrides
things to consider when preparing a gas
- soluble or insoluble in water
- density compared to air
- reactivity with drying agents
State whether the following non-metals are oxidizing or reducing agents.
- hydrogen
- carbon
- chlorine
- oxygen
- sulfur
- nitrogen
- reducing agent
- reducing agent
- oxidizing
- oxidizing
- reducing
- reducing
How is oxygen prepared?
Decomposition of H2O2 in the presence of manganese oxide catalyst.
- concentrated H2O2 is slowly dropped from a dropping funnel into a sealed flask containing manganese oxide
- as the H2O2 decomposes, oxygen is produced and is collected in a gas jar by downward displacement of water, as oxygen is only slightly soluble in water
- if dry oxygen is required it is then passed over anhydrous calcium chloride in a U-tube and collected by upward displacement of air
how is ammonia prepared?
- warming any alkali usually, calcium hydroxie, with an ammonium salt such as ammonium chloride or ammonium hydroxide
- the ammonia gas produced is passed over calcium oxide in a U-Tube and collected in a gas jar by downward displacement of air.
when preparing ammonia, why is it not passed through water?
it is very soluble and will react with water
when preparing ammonia, why is it passed over calcium oxide?
calcium oxide serves to remove water to obtain anhydrous ammonia
when preparing ammonia, why is glass jar inverted?
ammonia is lighter than air and so is collected by downward displacement of air
what gas/gases can the apparatus below be used to prepare?
- Idenitify the labels
- what is the role of C and E
- Used to prepare ammonia
A - ammonia gas
B - gas jar
C - damp litmus paper for idenitfying ammonia (turns blue)
D - U-tube
E- Calcium Oxide - drying agent to dry ammonia gas
F - reactants (mixture of ammonium salt(usually ammonium chloride) and a base (usually calcium hydroxide)
G - gentle heat
How is carbon dioxide prepared?
- dropping dilute HCl onto marble chips. this reaction produces a salt and carbon dioxide
- Carbon dioxide is passed over calcium chloride or concentrated sulphuric acid in a u-tube to dry it
- Carbon dioxide is then collected by upward displacement of air in a gas jar
why is carbon dioxide collected by upward displacement of air?
it is heavier than air
why can concentrated H2SO4 and anhydrous CaCl2 be used as drying agents for CO2 and O2, but not for ammonia?
Ammonia will react with concentrated H2SO4 and anhydrous CaCl2
when to invert the gas jar or not for collecting gases
- gas is a fluid and so the gas jar will fill from bottom to top.
- gases that are lighter than air will be displaced upward by air so the jar has to be inverted so that the gas can be collected at the ‘bottom’.
- gases that are heavier than air will be displaced downward by air so the jar will be upright so that the gas can be collected at the ‘bottom’.
what is the method of collecting gases that are more dense than air?
collected in a gas jar by upward displacement of air i.e. the gas jar is erect.
what is the method of collecting gases that are less dense than air?
they are collected by downward displacement of air, i.e. gas jar is inverted
Uses of Cabon dioxide
- fire extinguishers
- carbonated soft drinks
- dry ice
- aerosol propellant for certain foods such as whipped cream
Uses of Oxygen
- in medicine to treat varoius breathing disorders such as asthma to improve oxygentation of the cells. the oygen is delivered to lungs by oxygen masks.
- used in welding metals
- steel production
uses of carbon
- jewelry(diamond)
- pencils(graphite)
- drill bits(diamond)
- cutting glass(diamond)
- to make glass
- to make carbon fibre to reinforce plastics
uses of sulphur
- mainly to produce sulfuric acid
- used to harden(vulcanise) rubber tyres
- to make fungicides for plants
- to make match heads
uses of phosphorus
- to make pesticides
- to manufacture phosphoric acid
- to produce fireworks, flares and explosives
- to make fertilizers
- make matches and the striking surface of match boxes
uses of chlorine
- treat drinking water by killing bacteria
- to make insecticides eg DDT
- to make antiseptics
- to make fluids for dry cleaning
- to make bleaches
- for making PVC
uses of nitrogen
- refrigerant as liquid nitrogen
- manufacture ammonia
- to make fertilizers
- used as inert atmosphere for food packaging
uses of silicon
- making silicon chips for computers
- make glass
- to make jewelry eg emeralds
Harmful effects of Carbon dioxide
- greenhouse effect and global warming
- acidification of oceans resulting in destruction of coral reefs
harmful effects of sulphur dioxide
- respiratory problems
- forms smog which causes respiratory problems
harmful effects of carbon monoxide
- displaces from haemoglobin, decreassing the amount of oxygen in the blood.
harmful effects of oxides of nitrogen
- acid rain
- lung damage
- damages leaves reducing plant growth
Harmful effects of Hydrogen Sulfide
- irritates eyes and repiratory system
- combines haemoglobin and reducing it oxygen carrying properties
harmful effects of carbon
- forms smog
- coats leaves of plants and slows photosynthesisi
Harmful Effects of nitrates andd phosphates
- excessive growth of algae leading to eutrophication
solid waste is caused mainly from:
glass, rubber, paper and plastics
- broken glass can trigger fires by acting as a lens focusing light energy
- glass can injure animals
- printer ink , chlorine and bleaches from paper may be toxic and
- plastics can harm marine life.
what main characteristic of water accounts for many of its physical properties?
water is polar the partially positive charge on the hydrogen atoms attract the partially negative charge on the oxygen atoms forming so called hydrogen bonds. These hydrogen bonds are stronger than regular intermolecular forces
Are hydrogen bonds physical or chemical bonds?
physical bonds between water molecules
Physical properties of water
- relatively high melting and boiling points
- high heat of vapourization
- high specific heat capacity
- maximum density at 4 oC
- liquid at room temperature
- dissolves a large number of substances
How can the solvent properties of water be detrimental?
Harmful chemicals can dissolve in water polluting it or making it hard. Water can also dissolve and leach out important minerals from soils making them less fertile.
common water pollutants
- sulfur dioxide and oxides of nitrogen which dissolve in rain water to produce acid rain
- heavy metal ions especially from industries
- nitrate and phosphate ions from fertilisers and detergents
- organic compounds from farmyard waste and untreated sewage
- Pesticides
Leaching occurs as (1)_______ passes through soil and (2)_________ water soluble substances. This makes the soil (3)______
- water
- dissolves
- less fertile
what is meant by ‘hard’ water.
water with dissolved magnesium and calcium salts
two types of water hardness
temporary and permanent
Temporary hard water contains (1)_____________ and (2)___________. This kind of water is found in (3)____________ areas, and is formed when (4)___________ containing (5)___________ passes through limestone forming (1)___________. Permanent water hardness is formed when (6)___________ and (7)_________ are present. temporary hardness can be removed by (8)_________ while permanent hardness cannot.
- Calcium bicarbonate
- Magnesium bicarbonate
- limestone-rich
- rainwater
- dissolved carbon dioxide
- calcium sulphate
- magnesium sulphate
Steps in the treatment of water for domestic use
- Flocculation: clumping of smaller particles together to form larger particles called floc
- Sedimentation: floc allowed to settle
- Filtration: clear water above the floc passed through filters to remove remaining particles and some microorganisms such as bacteria and viruses
- Chlorination: chlorine gas or monochloroamine added to kill remaining microorganisms
methods to treat water in the home
- boiling
- filtering
- chlorinating - adding sodium chlorate and calcium chlorate tablets
How to soften hard water
- Boiling - only removes temporary hardness
- Adding sodium carbonate - removes both types of hardness
- Ion exchange- removes both types of hardness
- Distillation - removes both types of harness
- Reverse osmosis - removes both types of hardness
