Periodic Table of Elements

• The atomic mass of an element is the weighted average mass of all the isotopes of that element.
• Isotope - Atoms with same number of protons but different numbers of neutrons
• Periods (rows) represent increasing nuclear charge and decreasing size of atoms.
• Elements are arranged into groups (columns) based on similarities in electronic structure and chemical behavior.
• Elements in the same period have the same electron shell configuration.
• Atomic number = Number of protons
• The periodic table is an arrangement of the elements according to their atomic number, electron configuration, and chemical properties.
• Atomic Number (Z) = # of Protons
• Mass Number (A) = # of Protons + Neutrons
• The symbol for hydrogen is H. Atomic number: 1. Atomic Mass: 1.01. Classified as Non-Metals.
• The symbol for nitrogen is N. Classified as Non-Metals. Atomic number: 7. Atomic mass: 14.01. Part of Nitrogen group.
• Group 1 elements are called alkali metals because they form salts when combined with acids.
• Group 2 elements are called alkaline earth metals due to their ability to neutralize acidity.