Atoms/elements

• Subatomic


  Below the atomic level
• Protons


  Positively charged subatomic particles found in the nucleus of an atom
• Electrons


  Negatively charged subatomic particles that move around the nucleus of an atom
• Neutrons


  Neutrally charged subatomic particles found in the nucleus of an atom
• Positively


  Having a positive charge
• One element has one type of atom
• Two elements have two types of atoms
• Negatively


  Having a negative charge
• Levels


  Energy levels of electrons around the nucleus of an atom
• 1/1850 of the mass of an atom is due to electrons
• An atom is neutral when the number of protons equals the number of electrons
• Hydrogen's nucleus does not contain neutrons
• An atom is not empty, it contains protons and neutrons in the nucleus and electrons around it</b>
• Atomic Number


  The number of protons in the nucleus of an atom
• The atomic number determines the element
• Isotopes have the same number of protons but different mass numbers
• The mass of an atom is almost entirely due to protons and neutrons
• The mass of an electron is tiny, about 1/1850 of the mass of an atom
• Symbol


  A one or two-letter abbreviation for an element
• Examples of symbols: Fe for iron, Cl for chlorine
• Old languages have different names for elements
• Chlorine is a yellowish-green gas