Key words: protons, neutrons, electrons, atomic number, proton number & periodic table.
The nucleus of an atom is made of PROTONS and NEUTRONS.
Protons = Positive
Electrons = Negative
The atomic number of an element = the number of protons in the nucleus of the atom
THE ARRANGEMENT OF ELECTRONS
Electrons in atoms are in energy levels that can be represented by shells
Electrons in the lowest energy level are in the shell closest to the nucleus
Electrons occupy energy levels from the lowest first, the first group can only have 2 electrons then 8 in the second and 8 in the third etc.. Eg sodium = 2, 8, 1.
- All the electrons in a group of the periodic table have the same number of electrons on their highest energy level (outer shell)
Compounds are substances in which elements are chemically combined. When elements react their atoms achieve stable arrangements of electrons
Atoms gain or lose electrons to form ions or share electrons to form covalent bonds
COVALENT = SHARE.
IONIC = GIVE AND TAKE.
Ionic bonds hold compounds made of ions together.
Other compounds are held together by covalent bonds
COMPOUNDS MADE OF IONS HAVE GIANT STRUCTURES THAT ARE VERY REGULAR.
STRONG FORCES OF ATTRACTION ACT THROUGHOUT THE LATTICE TO HOLD THE IONS TOGETHER