Periodic Square Station Atomic number = # of protons in an atom. This is the identifying number of an element 6 Atomic mass = # of protons AND neutrons in the nucleus of an atom. The atomic mass is usually a decimal, but we round to the nearest whole number to find the number of neutrons.

Why does the nucleus have a positive charge?? Protons - positively (+) charged subatomic particle found in the nucleus of an atom Neutrons - neutral (no charge) subatomic particle found in the nucleus of an atom Electrons - negatively (-) charged subatomic particle that orbits around the nucleus in the electron cloud valence electrons - electrons on the outermost shell of the electron cloud (valence electrons determine whether or not an atom will bond with another atom!) nucleus - contains protons and neutrons at the center of an atom. This is where the mass of an atom comes from. Why does the nucleus have a positive charge??

atomic number - number of protons in an atom neutral atom - an atom with an equal number of protons (+) and electrons (-). This means the atom has NO charge! Ion - an atom with a charge. This means an atom has an unequal number of protons and electrons. Isotope - an atom with a different number of neutrons than it usually has atomic number - number of protons in an atom atomic mass - number of protons and neutrons in the nucleus of an atom Think about it… do you think the number or protons, or electrons, of the atom changed?? Why??

(Valence electrons are a type of electron) Parts of the atom & Valence electron chart Part of the atom (aka subatomic particle) Location Charge protons nucleus Positive (+) neutrons Neutral (no charge) electrons Electron cloud Negative (-) Valence electrons (Valence electrons are a type of electron) Outermost shell of the electron cloud

Atomic models

Challenge station Which two particles are responsible for the mass of an atom? The protons and neutrons that are in the nucleus of an atom! Which two subatomic particles determine the charge of an atom? The protons and electrons, since those are the only two subatomic particles with charges. If the (+) protons = (-)electrons, then the atom is neutral or has no charge since the opposite charges cancel. But if the atom gains or loses electrons, the atom will become an ion (an atom with a charge). How is an element’s atomic number like a person’s fingerprints? The atomic number = the number of protons. The number of protons gives the atom its’ identity, similar to our fingerprints identifying who we are. (each element has a specific number of protons). How are isotopes of an element alike? They have the same number of protons. How do two different isotopes of the same element differ? They have a different number of neutrons. Ex: Uranium usually has 146 neutrons, but some versions of uranium could have more, or less, neutrons than that