Mass Number Isotopes Ion Elements on the periodic table are made of atoms. Atoms are the smallest form of matter. All atoms in an element look the same. The structure of an atom determines how that atom will react with other atoms of a different element Atom: Element: 8 O 15.99999 Proton = p+ Electron = eNeutron = n0 Atomic # is the number at the top of each block on the periodic table Atomic # = #p Neutral Atom #p = #e- 1 H 1.00784 Mass # = protons + neutrons always a whole number NOT on the Periodic Table! © Addison-Wesley Publishing Company, Inc. Each element has billions of atoms so it is important to name each one correctly. Naming a single atom is called atom notation 1. Nuclear Symbol: Mass #atomic #symbol 2. Hyphen Notation: element name – mass # Hyphen notation: carbon-12 Nuclear symbol: Mass # Atomic # 12 6 C REMEMEBER!!! # p = atomic # Mass # = #p + #n Hyphen Notation: Oxygen – 16 Nuclear Symbol: 16 8 O Chlorine-37 › atomic #: 17 › mass #: 37 › # of protons: 17 › # of electrons: 17 › # of neutrons: 20 37 17 Cl Remember: Neutral = same number of (+) and (-) Neutral Atom = same number of p+ and e- Atoms are not always neutral. Sometimes emove around – this causes and atom to become an ion. An atom with an unequal amount of p+ and e- causes a charge to form Loses e- (More protons) = (+) charge Gains e- (More electrons) = (-) charge The quantity of the electrons lost or gained determines the charge quantity Ion Neutral atom Ion Neutral atom An ion can only be named using the nuclear symbol or if the picture is given. Nuclear Symbol: 19 9 F -1 You cannot identify an ion or name an ion by hyphen notation. Oxygen - 16 › atomic #: 8 › mass #: 16 › # of protons: 8 › # of electrons: 10 › # of neutrons: 8 16 8 -2 O Remember: an element is made of billions of tiny atoms. (602,000,000,000,000,000,000,000) Atoms all look alike (same #p) Atoms do not weigh alike (different mass#) Atom: Element: 12 12 148 12 12 12 12 12 12 14 8 12 Carbon – 12 Carbon – 14 © Addison-Wesley Publishing Company, Inc. All elements have isotopes meaning all elements are made of tiny atoms that have different masses.