1.Matter

a- Types of matter, physical states of matter, physical properties of matter. Chemical properties of the matter

We can classify the matter according to its physical state and there are 3 types of physical state: gases, liquids and finally solids. Gases have a variable shape and volume; liquids have a constant volume and variable shape and solid have constant shape and volume.

Then we can also classify the matter into 2 groups: pure substances and mixtures. Pure substances can be elements or compounds, and mixtures can be homogeneous, colloidal, or heterogenous according to the size of the molecules of the solute.

We can make happen physical changes in state of matter. There are 2 types of physical changes, one in which there is an input and the other in which there is a release of energy. Melting, boiling, and sublimation require energy to happen and on the opposite side, condensation, freezing and deposition release energy.

Matter possesses several physical properties.

Melting point (intensive physical property)è Melting point is the temperature at which matter begins to change from a solid-state to a liquid state.

Freezing point (intensive physical property è Freezing point is the temperature of a liquid at which it changes its state from liquid to solid at atmospheric pressure. In this state, liquid and solid exist in equilibrium

Boiling point (intensive physical property è Boiling point is the temperature at which matter begins to change from a liquid state to a gaseous state.

Density (intensive physical property è Density is the mass of unit volume of a substance, or it is mass of one cubic centimetre of a substance.

Chemical properties of matter are toxicity, oxidation states, heat of combustion, chemical stability, flammability, coordination number, reactivity, enthalpy of formation and possible chemical bonds, solubility, degree of ionization, electronegativity, acidity/basicity. Matter can include proton, atoms, mols, compounds, humans…

b- Pure substances and mixtures. An element, a compound.

Pure substances and mixture are opposite. Pure substance refers to an element or a compound that has no component of another compound or element. Pure substances are made of only one type of atom or molecule. A mixture is a combination of 2 or more substances that don’t chemically bond. We can oppose particularly a compound and a mixture. Where a compound present different elements which are in fixed proportions, in a mixture, the proportions of the different elements can be varied. In a compound, it is difficult to separate into elements which make it up, but in a mixture, elements can be separated. The properties of a compound are different from the properties of the elements whereas in a mixture, its properties are those of elements making it up. Finally, energy is usually giver or taken in when a compound is formed, and no energy is gained or lost when a mixture is made.

An element is the simplest form of a pure substance, pure substance is made of only one type of atom or molecule. A compound is a substance composed of 2 or more elements that have been joined by chemical bonds.

c- Composition of the atom (atomic particles, nuclide, isotope, atomic number, and mass number)

Each element consists of unique atoms, which is the smallest unit of matter that still retains the properties of an element. Atoms (r= m) are composed of subatomic particles: the nucleons and the electrons. Nucleons form the atomic nucleus and can be divided into 2 types: neutrons (no electrical charge) and protons (positive charge). The electrons (negative charge) form a cloud around the nucleus (r=m).

A nuclide is an element made up of atoms that have the same number of protons and neutrons. An isotope are elements made up of atoms that differ in the number of neutrons (ex: carbon-12 with p=6 and n=6, carbon-13 with p=6 and n=7 and carbon-14 with p=6 and n=8). Atomic number characterises the number of protons in the nucleus, the number of electrons in the cloud around the nucleus and the order o an element in a periodic table. Mass number characterises the number of nucleons, the total number of protons and neutrons in the atom.

d- The atomic mass, the atomic mass unit, the relative atomic mass, molecular mass, and relative molecular mass

The atomic mass is the mass of an atom. The atomic mass unit or AMU is a physical constant equal to one-twelfth of the mass of an unbound atom of carbon-12. It is a unit of mass used to express atomic masses and molecular masses. The symbol for the unit is u (unified atomic mass unit) or Da (Dalton), although AMU may still be used. The relative atomic weight is a physical quantity defined as the ratio of the average mass of atoms of a chemical element in a given sample to the atomic mass constant. Molecular mass is the sum of the atomic weights of the atoms in a molecule. The relative molecular weight is the ratio between the molecular weight of a molecule and the atomic mass unit.

e- Amount of substance, mole, Avogadro’s number, molar mass, molar V of gas

The amount of substance is defined as the quantity or number of discrete atomic-scale particles in it divided by the Avogadro constant NA. one mol contains exactly 6,02214076 × elementary entities. This number is the fixed numerical value of the Avogadro’s number, it’s a constant. It is the number of constituent particles (usually molecules, atoms, or ions) in a sample with the amount of substance in that sample. Molar mass is the mass of 1 mole of a substance, numerically equal to the molecular weight. It is expressed in g/mol. At a given temp and pressure, 1 mole o a gas occupies the volume =molar gas volume. It is the ratio of the volume occupied by a substance to the amount of substance, usually given at a given temperature and pressure.