What are atoms

What are atoms

1. Atoms are the basic structural units of elements

   • An element is a substance that cannot be separated into simpler substances, and cannot be converted into another substance by ordinary chemical reactions.
   • An atom is the smallest unit of an element, and each atom retains all the chemical properties of that element.

2. Atoms are composed of still smaller particles.

   • Atoms are composed of subatomic particles: neutrons (n) which have n o charge; protons, which each carry a single positive charge, neutrons, which carry a single negative charge.
   • Subatomic particle are so small that they are assigned their own unit of mass, measured in atomic mass nunits.
     • The mass number of an atom is the total number of the protons and neutrons in its nucleus.
   • Protons and neutrons cluster together in the center of the atom, forming the atomic nucleus.

3. Isotopes are atoms of the same element with different number of neutrons

   • Atoms of the same element with different number of neutrons are called isotopes.
   • Isotopes can be distinguished from one another because each has a different mass number, which is written as a superscript preceding the atomic symbol.
   • Some Isotpes are radioactive
     • Radioactive meaning that their nuclei spontaneously break apart, or decay.