Unit 1 Chemistry

Unit 1 Chemistry

1. Atoms Elements and Compunds

   • All substances are made of atoms
   • Elements are made of only one type of atom
   • Chemical symbols are used to represent atoms
   • Compounds contain more than one element

2. Atomic Structure

   • The nucleus of an atom is made of protons and neutrons.
   • Protons have a positive charge, electron a negative charge and neutrons are not charged. The atomic number(or proton number) of an element is equal to the number of protons in the nucleus of its atoms
   • Elements are arranged in order of their atomic numbers in the periodic table. The mass number is the sum of the protons and neutrons of an atom.