2.1 Matter

2.1 Matter

Matter Anything that occupies space and has mass

Matter

Element

Atom

Compound

Molecule

Molecule

Ion

Particulate nature of matter Tiny and discrete Diffusion proves that matter is made up of tiny particles.

Kinetic theory of matter Matter consists of tiny, discrete particles that are constantly moving. The particles move in a random motion and collide with one another.

Diffusion

Change of state

Heating graph

Completely melted

Completely vaporised Even heating Melting point > 100°C?

Cooling Graph

Energy lost = heat energy released Even cooling

Comparison

2.2 Atomic structure

2.2 Atomic structure

Subatomic Structure

Atomic Structure Proton number = number of protons Nucleon number = no. of neutrons + no. of proton

Symbol of Elements

2.3 Isotopes The Isotopes of an element are the atoms of that element which contain the same number of protons but a different number of neutrons.

The Uses of Isotopes  Medical  (a) Cobalt-60 are used in radiotherapy  (b) Iodine-131 can be injected into the thyroid gland of patient with hyperthyroidism (over-active thyroid gland) to destroy the hyperactive thyroid cells.  (c) Sodium-24 is injected into the body to identify the location of a blood clot.  (d) Carbon-14 are used in determine the age of fossil.

2.4 The Electronic Structure of an Atom 1 The electron configuration (electron arrangement) of an atom is the arrangement of electrons in shells (orbits) around that atom's nucleus.

2.4 The Electronic Structure of an Atom 2 The electrons in an atom are arranged in shells around the nucleus. The maximum number of electrons which can fill a particular shell is as follows:

2.4 The Electronic Structure of an Atom 3 The electrons in the last shell of an atom are known as valence electrons. They determine the chemical properties of the element.

2.4 The Electronic Structure of an Atom 4. Sulphur has 16 electrons: The electronic configuration or electron arrangement is then written as 2.8.6.

2.4 The Electronic Structure of an Atom 5 All elements having the same valence electrons will show the same chemical properties, for example, chlorine and bromine, have 7 valence electrons, will exhibit similar chemical properties.

2.4 The Electronic Structure of an Atom 6 Helium has a complete shell of 2 valence electrons or duplet condition. Similarly, neon and argon also have complete shells. They have 8 valence electrons or the octet condition. These elements are monoatomic and are very stable gases.

2.4 The Electronic Structure of an Atom 7 The electron arrangement of an element, for example;Na is constructed by drawing 3 circles around the nucleus to represent each shell, as its electron configuration is 2.8.1. Thus we have

2.4 The Electronic Structure of an Atom 8 Table 2.5 shows the electron arrangement of the first 20 elements in the Periodic Table.

2.4 The Electronic Structure of an Atom