Chapter 1 science

• Atoms are the building blocks of all materials. It consists of protons and neutrons which are surrounded by electrons
• The atomic number is the number of protons in the nucleus of an atom. This determines what type of atom it is
• Mass number is the total number of protons and neutrons in an atom's nucleus.
• Elements are substances made up of only one type of atom.
• Ions are atoms that have gained or lost electrons, and are therefore charged.
• Molecules are clusters of atoms that make up an element or a compound.
• Compounds are pure substances that are made up of two or more different types of atoms chemically joined.
• Crystal lattice is a grid-like structure of atoms or ions in which each particle is bonded to all of its neighbouring atoms.
• • Carbon is the only non-metallic element that can form crystal lattices.
• • Atoms are made up of even smaller particles known as

  subatomic particles.
• • The number of neutrons is the mass number minus the atomic number.
• • The electrons are much smaller and lighter, they move very fast around the nucleus to form an electron cloud that surrounds the nucleus.
• • The negative charge of electrons causes them to be attracted to the positively charged protons in the nucleus. This is because opposite electric charges attract each other, The

  attractive force is known as electrostatic attraction.
• • Atoms can only be seen by a scanning tunnel microscope or STM.
• • If an atom loses an electron, then it has a positive charge. This ion formed is called a cation.
• • If the atom gains electrons, then it has a negative charge. This ion formed is called an anion