Atoms and Molecules notes

 Atoms:

• Atoms are the basic building blocks of matter.
• They consist of a nucleus containing protons and neutrons, surrounded by electrons.
• Protons have a positive charge, neutrons have no charge, and electrons have a negative charge.
• The atomic number represents the number of protons in an atom, while the atomic mass is the sum of protons and neutrons.

Molecules:

• When atoms combine chemically, they form molecules.
• Molecules are the smallest units of compounds and retain the properties of that compound.
• For example, water (H2O) is made up of two hydrogen atoms and one oxygen atom chemically bonded together.

Atomic Structure:

• The nucleus of an atom contains protons and neutrons, while electrons orbit around the nucleus in specific energy levels or shells.
• The number of electrons in the outermost shell determines an element's reactivity and how it will bond with other atoms.

Chemical Bonds:

• Atoms combine through chemical bonds to form molecules.
• Types of bonds include covalent bonds (sharing of electrons), ionic bonds (transfer of electrons), and metallic bonds (electrons moving freely between atoms).

Law of Conservation of Mass:

• In a chemical reaction, atoms are rearranged to form new substances, but the total mass remains constant.
• This principle is known as the Law of Conservation of Mass.

Atomic Models:

• There are various atomic models developed over time, including Dalton's atomic theory, Thomson's plum pudding model, Rutherford's nuclear model, and Bohr's atomic model.