-
8/10/2019 20121001211031Topic 2.pptx
1/23
TOPIC 2: ATOMS,ELEMENTS ANDCOMPOUNDS
by
Najmiyatul Fadilah Mohamad
-
8/10/2019 20121001211031Topic 2.pptx
2/23
LEARNING OUTCOMES
By the end of this topic, you should be able to:
1. Identify how matter is classified based on its atoms
2. Differentiate between metals and non-metals
3. Write the chemical symbols for elements
4 . Write the formula of molecules for elements and compounds
5. Identify similarities and differences between elements,
compounds and mixtures.
6. Describe alloys
7. Differentiate between solution, solute and solvent.
-
8/10/2019 20121001211031Topic 2.pptx
3/23
NATURE OF ATOMS, ELEMENTS,
COMPOUNDS AND MIXTURES
Living things/ non-living thing
Made of atoms= tiny & small building block of matter.
composition structure
kinds of atoms it contains arrangement of these atoms
classified and described :
(i) according to its physical state as a gas,liquid or solid (which has been discussed in Topic 1)
ii) according to its composition either pure substances or mixtures
-
8/10/2019 20121001211031Topic 2.pptx
4/23
Classification of matter
-
8/10/2019 20121001211031Topic 2.pptx
5/23
Pure Substances
A pure substance (usually referred to simplyas a substance) is matter that has a fixedcomposition and distinct properties.
-
8/10/2019 20121001211031Topic 2.pptx
6/23
Element
An element is a substance which cannot bebroken down into simpler substances bychemical or physical methods.
(i) It consists of only one type of atom
(ii) It cannot be broken down into simplersubstances either by physical or chemical
means
(iii) It can exist either as individual atoms ormolecules as shown in Figure 2.2.
-
8/10/2019 20121001211031Topic 2.pptx
7/23
Molecule
A molecule consists of two or more atoms ofthe same element or different elements,which are chemically bound together.
What are 3 groups of elements?
-
8/10/2019 20121001211031Topic 2.pptx
8/23
-
8/10/2019 20121001211031Topic 2.pptx
9/23
-
8/10/2019 20121001211031Topic 2.pptx
10/23
Mixture
(a). Homogeneous Mixture
Is a mixture in which the mixing is uniform andtherefore has a constant compositionthroughout the mixture. The component are
indistinguishable.
(b). Heterogeneous Mixture
Is a mixture in which the mixing is not uniformand therefore has regions of differentcompositions. The components aredistinguishable.
-
8/10/2019 20121001211031Topic 2.pptx
11/23
-
8/10/2019 20121001211031Topic 2.pptx
12/23
Differences Between Metals
and Non-Metals
Metals Non-Metals
Solid at room temperatureExcept mercury
Gases, liquid or solid at roomtemperature
Silvery shine Not silvery, several brightly
Generally malleable and ductile Brittle
Good conductors of heat and electricity Poor conductors of heat and electricity
Basic oxides Acidic oxide
-
8/10/2019 20121001211031Topic 2.pptx
13/23
Chemical Symbols of Elements
In the form of one or two letters.
First letter always capitalised.
Second letter is lowercase.
-
8/10/2019 20121001211031Topic 2.pptx
14/23
Formulae of Molecules for
Elements and Compounds
Molecule made up of 2 atoms = diatomicmolecule.
Molecule formulae = actual number and typesof atoms in molecule.
Molecular compound = compound that
composed of molecule that contain morethan one type of atom.
-
8/10/2019 20121001211031Topic 2.pptx
15/23
Similarities And Differences of
Elements, Compounds and Mixtures
Refer page 42, Table 2.8
-
8/10/2019 20121001211031Topic 2.pptx
16/23
Alloys
Mixture of two or more elements.
Both can be metals.
One can be metal and another a non-metal.
Mixtures are homogenous
Prepared by heating and bonding the metals
together. The resultant alloy has completely different
properties from the starting metals.
-
8/10/2019 20121001211031Topic 2.pptx
17/23
Alloys
A metal structure
The metal structure before and after a force is applied to it
Structure of an alloy
-
8/10/2019 20121001211031Topic 2.pptx
18/23
Solution
Is a homogenous mixture of two or moresubstances.
Dissolve substances = solute
Liquid = solvent
A solution is a mixture obtained by dissolvingsubstances, called the solute, in anothersubstance called the solvent.
-
8/10/2019 20121001211031Topic 2.pptx
19/23
Solution
-
8/10/2019 20121001211031Topic 2.pptx
20/23
-
8/10/2019 20121001211031Topic 2.pptx
21/23
Three categories of Solution
Dilute solution has little solute particles dissolved in the solvent.
Concentrated solution When we add more solute into the solvent, it can
still dissolve.
Saturated solution we keep on adding the solute into the solvent until
it reaches a level where the solute cannot dissolveany more at that particular temperature.
-
8/10/2019 20121001211031Topic 2.pptx
22/23
Dilute, concentrated and
saturated solutions
-
8/10/2019 20121001211031Topic 2.pptx
23/23
Factors Affecting Solubility
(a) Size of the solute particles
(b) Type of the solvent
(c) Temperature of the solvent
