Chemistry is the study of the composition, structure, properties and interactions of matter. Matter is basically “everything around us”.
Physical property refers to the physical characteristic of matter which can be observed or measured without changing its composition. Examples of physical properties: state of matter (solid, liquid or gas), melting point, boiling point, density, colour, solubility, mass, volume, concentration, electrical conductivity, thermal conductivity… Chemical property refers to the characteristic of matter which enables […]
Physical change refers to changes to the physical appearance of matter that does not alter its chemical composition. Examples of physical changes: ice melting, water boiling (changes in the states of matter), sugar dissolves in water… Chemical change refers to changes to the chemical composition of matter which results in the formation of new […]
Matter Matter is anything that occupies space and has mass. Matter exists in the form of solid, liquid and gas.
Particle Theory of Matter states that matter is made up of a large number of tiny and discrete particles. The particles may be atoms, molecules or ions. *Atoms are the smallest particle of an element. *Molecules are particles that made up of two or more atoms of the same or different element. *Ions are […]
An element is a substance that made up of only one type of atom. A compound is a substance that contains 2 or more elements that are chemically bonded together in a fixed ratio.
Kinetic Theory of Matter states that all matter is made up of tiny particles (atoms, molecules or ions) that are in constant motion. *Solid particles have low kinetic energy. *Liquid particles have higher kinetic energy than solid particles. *Gas particles have the highest kinetic energy.
Diffusion is a process in which particles of a substance move from an area of high concentration to an area of low concentration until the concentration of the 2 areas becomes equal. Diffusion occurs in solid, liquid and gas.
Matter exists in 3 physical states: solid, liquid & gas. Solid has fixed volume, fixed shape, & cannot be compressed. Solid particles are packed very closely together in an orderly manner. Solid particles can only vibrate at their fixed positions. There are strong forces of attraction between the solid particles. Liquid has fixed […]
Melting: solid changes into liquid; Freezing: liquid changes into solid; Boiling/ Evaporation: liquid changes into gas; Condensation: gas changes into liquid; Sublimation: solid changes into gas; Desublimation/ Deposition: gas changes into solid.
An atom is made up of 3 subatomic particles: protons, neutrons & electrons. Protons carry a positive electrical charge. Electrons carry a negative charge. Neutrons carry no charge. Protons & neutrons locate in the centre of an atom. Together they form the nucleus of an atom. Electrons move at high speed in shells surrounding the nucleus. […]
Proton number is the number of protons in the nucleus an atom. Proton number is also known as atomic number. Nucleon number is the number of protons and the number of neutrons in the nucleus an atom. Nucleon number is also known as mass number. Note: From this equation, we […]
Isotopes are atoms of the same element with the same number of protons, but different numbers of neutrons. Isotopes are atoms of the same element with the same proton number, but different nucleon numbers.
Electrons move around the nucleus of an atom in shells (energy levels). Each shell (energy level) can only hold a certain number of electrons. For the first 20 elements in the Periodic Table: The 1st shell can hold a maximum of 2 electrons; the 2nd shell can hold a maximum of 8 electrons; the […]
Valence electrons are electrons in the outermost shell of an atom. The outermost shell of an atom is also known as the valence shell. Valence electrons are the electrons that participate in chemical reactions. Therefore, elements that have the same number of valence electrons will also have similar chemical properties.