S1 SCI CHAP 3 CHEMICAL COMPOSITION

Question 1

What are elements?

Answer 1

Elements are the basic building blocks of living and non-living matter. They are pure substances that cannot be broken down into two or more simpler substances by chemical methods, and they only consist of one type of atom.

Question 2

What is the periodic table of elements?

Answer 2

The P.T.E. is an arrangement of elements in order of their chemical properties. It consists of a total of 18 groups and 7 periods. The elements are represented by their chemical symbols and are also split into metals and non-metals.

Question 3

How do we differentiate groups and periods in the P.T.E.?

Answer 3

The P.T.E. consists of a total of 18 groups and 7 periods. Elements that are arranged in the same vertical column are in the same group with similar chemical properties, while the elements that are arranged in the same horizontal row belong to the same period. As we move from the left to the right of a period, the properties of the elements gradually change from those of metals to those of non-metals

NOTE: 1 way to rmbr p and g would be to suit the longer word with horizontal (longer word compared to vertical) and the shorter to vertical (shorter word compared to horizontal) or 2. shorter word (group) goes with the larger number (18)

Question 4

Go to: https://tinyurl.com/PTECHEM Where does the line differentiating metals and non-metals go?

Answer 4

search up

Question 5

Characteristics of metal and non-metal elements.

Answer 5

Metals are good conductors of heat and electricity and are typically solids with HIGH melting and boiling points. Some metals are also attracted to magnets. Non-metals tend to have lower melting and boiling points (with the exception of carbon and silicon), do not usually conduct electricity (with the exception of carbon and silicon), and are typically poor conductors of heat.

Question 6

How are elements formed?

Answer 6

They are formed mostly by a naturally occurring process.

Question 6

What are compounds and their characteristics?

Answer 6

A compound is a pure substance comprising two or more different elements chemically combined (chemical reaction). The property of the compound will differ from the 2/more constituent elements (elements it is formed by). Additionally, the elements in the compound react only in a fixed proportion by mass (e.g. H20 meaning 2 units of hydrogen and one unit of oxygen). Moreover, The compound cannot be broken down by physical methods (filtration, evaporation, etc.). It can only be separated by chemical methods.

Question 7

What are mixtures and their characteristics?

Answer 7

A mixture consists of 2/more elements and/or compounds that are mixed, but not chemically combined. The properties of a mixture are the complete opposite of that of a compound. 1. A mixture has the properties of the substances it is made of 2. The components of a mixture are not mixed in any fixed proportion 3. A mixture can be easily separated by physical methods such as filtration or evaporation 4. There is not specific name or formula for a mixture.

Question 8

Are H2 and O2 etc. compounds?

Answer 8

No. Firstly, a compound is formed by 2/more DIFFERENT elements chemically combined, whereas H2/O2 only consists of one type of atom. Moreover, the product of the new compound must differ from its constituent elements, which in this case, does not.

Question 9

Break down matter into its various types.

Answer 9

MATTER ->ELEMENTS,COMPOUNDS,MIXTURES -> (elements) METALS, NON METALS and (mixtures) SOLUTIONS,SUSPENSIONS

Question 10

What is the ‘staircase’ in the PTE used for?

Answer 10

The staircase differentiates the metal elements and the non-metal elements.

Question 11

Give any example of an element, compound, and mixture.

Answer 11

any element, compound, and mixture

Question 12

Name one suspension and one solution.

Answer 12

e.g. milo, salt solution

Question 13

examples of physical methods.

Answer 13

Filtration, distillation, fractional distillation, evaporation to dryness etc.

Question 14

example of a mixture only made up of elements, a mixture only made up of compounds, and a mixture made of both elements and compounds.

Answer 14

elements: steel
(iron+carbon+others)
compounds: Salt+water
(NaCI+H2O)
both: seawater (salt+water+magnesium chloride+small amts of iodine)

Question 15

state the formation of elements, compounds, and mixtures.

Answer 15

ele: mostly a naturally occuring processes
com: chemical reaction
mixtures: physical change

Question 16

State solution’s definition.

Answer 16

a solution is a mixture in which a substance completely dissolves in another substance (solute, solvent)

Question 17

state suspension’s definition.

Answer 17

a suspension is a mixture that contains insoluble substances in a solvent.

Question 18

Characteristics of suspensions.

Answer 18

Insoluble substances can be seen, light cannot pass through fully, and insoluble substances can settle to form deposits.

Question 19

What is rate of dissolving and what factors affect it?

Answer 19

Rate of dissolving refers to how fast a solute takes to fully dissolve in a solvent.

The three main factors affecting it:
1. Temp of solvent (the higher the faster)
2. Size of solute particles (the smaller the faster)
3. Rate of stirring (the higher the rate, fast rate of dissolving)

Question 20

What is solubility and what are the three factors that affect it?

Answer 20

Solubility refers to how well/ how much of a solute dissolves in a fixed volume of a particular solvent.

1. Type of solute
2. Type of solvent
   3.temp of solvent

Question 21

Solid B is red and has a fixed composition. It decomposes into two elements when heated. What is solid B? elem, comp, or mixt?

Answer 21

compound

Question 22

Show an appreciation of how recycling and reuse of precious materials can be facilitated by the classification of waste products based on their chemical composition.

Answer 22

irdk

Question 23

Show an awareness of the importance of knowing the chemical composition of everyday items and how it can be beneficial.

Answer 23

Melamine, which contains nitrogen and is deadly if consumed in large doses, has been added in milk powder products previously by manufacturers to make the protein levels of the milk powder appear higher. This has caused and will cause infants to be hospitalised and suffer from kidney diseases, and some even dying. ….

Question 24

Define the term solute.

Answer 24

A solute is a substance that dissolves in a solvent.

Question 25

Define the term solvent.

Answer 25

A solvent is a substance in which the solute dissolves.

Question 26

Characteristics of a solution.

Answer 26

The particles of the solution cannot be seen. The solute does not settle to form solid deposits. Finally, light can pass through through the solution fully.

Question 27

definition of malleable

Answer 27

The quality of typically a metal that is able to be hammered or pressed into shape without breaking or cracking.

Question 28

Do you think solutions and suspensions are mixtures? Explain your answer.

Answer 28

Yes, both solutions and suspensions are mixtures as they do not need to be mixed in a fixed proportion to be formed.

Question 29

State whether the following substance is a mixture. Explain your answer.

Seawater.

Answer 29

Yes, it’s a mixture of water and salt. If heated, the water will evaporate and leave behind the salt. Moreover, the mixture retains properties that of its constituents, water and salt.

Question 30

State whether the following substance is a mixture. Explain your answer.

Sulfur Dioxide.

Answer 30

No, it is a compound, comprising sulfur and oxygen chemically combined. The compound does not carry the same properties as its constituents, oxygen, and sulfur.

Question 31

State whether the following substance is a mixture. Explain your answer.

Magnesium.

Answer 31

No, it is not a mixture. Magnesium is an element. It consists of only one type of atom.