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