C. Johannesson Atomic Structure
Structure of the Atom Protons- Positively charged particles in the nucleus Neutrons-neutrally charged particles in the nucleus Electrons-negatively charged particles orbiting the nucleus C. Johannesson
A. Mass Number mass # = protons + neutrons © Addison-Wesley Publishing Company, Inc.
Structure of the Atom Atomic Mass-number of protons and number of neutrons Atomic Number- number of protons C. Johannesson
Structure of the Atom Symbols C. Johannesson
B. Isotopes Atoms of the same element with different mass numbers because they have different numbers of neutrons Mass # Atomic # Nuclear symbol: Hyphen notation: carbon-12
C. Johannesson B. Isotopes © Addison-Wesley Publishing Company, Inc.
C. Johannesson B. Isotopes Chlorine-37 atomic #: mass #: # of protons: # of electrons: # of neutrons:
C. Johannesson C. Relative Atomic Mass 12 C atom = × g 1 p= amu 1 n = amu 1 e - = amu © Addison-Wesley Publishing Company, Inc. atomic mass unit (amu) 1 amu= 1 / 12 the mass of a 12 C atom
C. Johannesson D. Average Atomic Mass weighted average of all isotopes on the Periodic Table round to 2 decimal places Avg. Atomic Mass
C. Johannesson Avg. Atomic Mass D. Average Atomic Mass EX: Calculate the avg. atomic mass of oxygen if its abundance in nature is 99.76% 16 O, 0.04% 17 O, and 0.20% 18 O amu
C. Johannesson Avg. Atomic Mass D. Average Atomic Mass EX: Find chlorine’s average atomic mass if approximately 8 of every 10 atoms are chlorine-35 and 2 are chlorine amu
What is an ion? If an atom has a positive or negative charge it is considered an ion It has either lost or gained electrons Cation-Postive Anion-Negative Cl - Mg 2+ C. Johannesson
Questions? “Nothing exists except atoms and empty space; everything else is opinion”Nothing exists except atoms and empty space; everything else is opinion C. Johannesson