Science

Science

1. Chem

   • Atoms
     • The Nucleus
       • It's in the middle of the atom.
       • It contains protons and neutrons.
       • The nucleus has an overall positive charge because protons are positively charged and neutrons have no charge.
       • Almost the whole mass of the atom is concentrated in the nucleus.
       • But size-wise it's tiny compared to the atom as a whole.
     • The Electrons
       • They move around the nucleus.
       • They have a negative charge (electrons and protons have equal but opposite charges).
       • They're tiny compared to the nucleus, but as they move around they cover a lot of space.
       • The size of their orbits determines how big how big the atom is.
       • They have virtually no mass.
       • They occupy shells (energy levels) around the nucleus.
     • Number of Protons Equals Number of Electrons
       • Neutral atoms have no charge overall.
       • The charge on the electrons is the same size as the charge on the protons, but opposite.
       • This means the number of protons always equals the number of electrons, but opposite.
       • The number of neutrons isn't fixed but is usually about the same as the number of protons.
     • Know Your Particles
       • Protons are heavy and positively charged.
       • Neutrons are heavy and neutral (no charge).
       • Electrons are tiny and negatively charged.
       • Protons has a relative maas of one and a relative charge of +1
       • Neutrons have a relative mass of one and a relative charge of 0
       • Electrons have a relative mass of 1/2000 and a relative charge of -1
   • Electron Shells
     • Electron Shell Rules