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Chapter 3 Chemical Foundations: Elements, Atoms, and Ions. Atoms, Ions and Isotopes. Learning Targets. You will learn about atoms, ions and isotopes. The atom. Symbols to be familiar with: Protons = p + Neutrons = n 0 Electrons = e - Atoms are always neutral
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Chapter 3Chemical Foundations: Elements, Atoms, and Ions Atoms, Ions and Isotopes
Learning Targets • You will learn about atoms, ions and isotopes.
The atom Symbols to be familiar with: • Protons = p+ • Neutrons = n0 • Electrons = e- • Atoms are always neutral • Neutral = Same number of protons and electrons
The symbol for an atom A X Z • A = the mass number (# p+ + n0) • X = symbol of element • Z = the atomic number (number of protons)
Funnies • Two molecules are walking down the street; one bumps into the other and says: • "Oh, my fault, you okay?” • The Second Molecule says: "No, I'm not ok, I've lost an electron!" So the first molecule says: "Are you sure" the second molecule answers, "I'm positive!"
Calculating mass number 1 equation rearranged: A = Z + neutrons Mass Number = # of protons + # neutrons OR A – neutrons = Z Mass number – neutrons = # protons OR A – Z = neutrons Mass number - # protons = # neutrons
Isotopes • Isotopes are atoms that have the same number of protons, different number of neutrons • Often represented as: element name – mass #. (Example: carbon – 14)
Practice • Give the number of protons, neutrons and electrons in the atom symbolized by 201 Hg 80 • Give the symbol to represent the following information: • The cesium atom with a mass number of 132
Try on your own • Give the number of protons, neutrons and electrons in the atom symbolized by 90 Sr 38 Strontium-90 occurs in fallout from nuclear testing. It can accumulate in bone marrow and may cause leukemia and bone cancer. • Give the symbol to represent the following information: • The iron atom with a mass number of 56
Ions • Ions are atoms with a charge • cations (positively charged ion) • anions (negatively charged ion) • Ions have a charge because they are gaining or losing electrons from their neutral atom • Symbol is element symbol with the ion charge as a superscript (Example: Ca2+) • Usually formed when metals combine with nonmetals
Examples • For each of the following ions, indicate the total number of protons and electrons in the ion (#46 in your book) A. Co2+ E. S2- B. Co3+ F. Sr2+ C. Cl- G. Al3+ D. K+ H. P3-
Examples-Answers • A. 27 p, 25 e B. 27 p, 24 e • C. 17 p, 18 e D. 19 p, 18, e • E. 16 p, 18 e F. 38 p, 36 e • G. 13 p, 10 e H. 15 p, 18 e
Homework • Atomic Structure Worksheet DUE MONDAY