SS1: CHEMISTRY - 1ST TERM
Introduction to Chemistry and Laboratory Apparatus | Week 15 Topics|1 Quiz
Nature of Matter | Week 23 Topics|1 Quiz
Separation Techniques I | Week 31 Topic|1 Quiz
Separation Techniques II | Week 45 Topics|1 Quiz
Particulate Nature of Matter I | Week 55 Topics|1 Quiz
Particulate Nature of Matter II | Week 69 Topics|1 Quiz
Symbols, Formulae & Oxidation Number | Week 77 Topics|1 Quiz
Laws of Chemical Combination | Week 84 Topics|1 Quiz
Chemical Equation & Chemical Combination (Chemical Bonding) I | Week 94 Topics|1 Quiz
Chemical Combination (Chemical Bonding) II | Week 104 Topics|1 Quiz
Chemical Combination (Chemical Bonding) III & Shapes of Covalent Molecules | Week 113 Topics|1 Quiz
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Elements, Compounds and Mixtures
Matter may be classified into elements, compounds, and mixtures.
An element is a substance which cannot, by any chemical process, be split up into two, or more, simpler substances. There are over 100 known elements scattered in different percentages all over the world. They occur naturally alone or in combination with other materials. Elements are arranged according to their atomic number in a table called a periodic table and may be classified into two groups, metals and non-metals. This classification also is based on the differences in their physical properties.
Examples include – oxygen, hydrogen, chlorine, sodium, magnesium, etc.
A compound is a substance which contains two or more elements, chemically combined together. Examples include water (H2O), carbon (IV) oxide (CO2), sodium chloride (NaCl), etc.
A mixture contains two or more constituents which can easily be separated by physical methods. The components of mixtures may be elements or compounds or both.
Types of Mixtures:
1. Homogenous Mixture.
2. Heterogeneous Mixture.
Homogenous Mixture: Sometimes called solutions, these are mixtures of relatively uniform composition, where the components are in the same phase, i.e. the constituent cannot be physically distinguished from one another. Examples are sugar solution, air, seawater, brass, salt solution, etc.
Heterogeneous Mixtures are mixtures in which their components are in different phases i.e the constituents can be distinguished from one another when mixed together e.g. kerosene and water, mud water, etc.
Other examples of mixtures are blood, crude oil, soil, urine, palm wine, milk, and coca-cola.
Differences between Mixtures and Compounds:
|1.||They may be homogenous or heterogeneous.||They are always homogenous.|
|2.||Constituent elements are not chemically bonded together and therefore can be separated by physical means.||Constituent elements are chemically bonded and cannot be separated by physical methods.|
|3.||Cannot be represented by chemical formula because the constituents are not in a fixed ratio.||Can be represented by chemical formula because the constituents are present in a fixed ratio.|
|4.||The properties of mixtures are a sum of their individual elements.||The properties of a compound differ from those of its component elements.|
1. (a) What is matter?
(b) Give three physical properties of matter.View Answer
2. Classify each of the following as physical change or chemical change
(i) Boiling of egg (ii) Melting of wax
(iii) Rusting of iron (iv) Digestion of Glucose
3. Write four examples in each case of
(a) Physical change (b) Chemical changeView Answer
4. (a) define the following: (i) Compound (ii) Mixture
(b)Give three differences between Compound and MixtureView Answer
5. (a) State the difference between a homogeneous mixture and a heterogeneous mixture
(b) Classify the following into homogenous and heterogeneous mixtures; Brine, Sweat, Muddy water, Table salt, Sand, BloodView Answer