Atomic Structure and the Periodic Table Lesson 2. August 13, 2012. Catalyst. Mystery Elements! Use your periodic table and the clues below to determine the identity of 3 mystery elements: This element, with a mass number of 207, is poisonous.
August 13, 2012
Atomic Symbol: Pb
Atomic Number: 82
Mass Number: 207.2
Atomic Symbol: Pt
Atomic Number: 78
Mass Number: 195.08
Atomic Symbol: S
Atomic Number: 16
Mass Number: 32.07
Sometimes, atoms of the same element have different numbers of neutrons. Atoms of the same element with different numbers of neutrons are called isotopes.
Ions are atoms with a net charge. The ion is charged because there are an unequal number of protons and electrons.
The atomic number always appears on the lower left side of the symbol.
Mass numbers are written on the upper left side of the symbol.
The charge on an ion is shown on the right side of the symbol.
Cl- Na+ Mg2+ Al3+ F- O2-