CHEM 1211K 1st Edition Lecture 5 Outline of Last Lecture I. Chapter 2 Atoms and Elements Chapter 2 Atoms and Elements (continued)II. Subatomic Particles: Protons, Neutrons, and Electrons in AtomsA. Each element has a unique number of protons in its nucleusB. The number of protons in the nucleus of an atom is called the atomic numberC. the elements are arranged on the Periodic Table in order of their atomic numbersD. Each element has a unique name and symbolE. symbol either one or two lettersF. one capital letter or one capital letter and one lowercase letter 2.6.4 IONS When atoms gain or lose electrons, they acquire a charge Charged atoms or groups of atoms are called ions When atoms gain electrons, they become negatively charged ions, called anions When atoms lose electrons, they become positively charged ions, called cations Ions behave much differently than the neutral atoms- e.g., the metal sodium, made of neutral Na atoms, is highly reactive and quite unstable; however, the sodium cations, Na+, found in table salt are very nonreactive and stable Because materials such as table salt are neutral, there must be equal amounts of charge from cations and anions in themIII. Structure of Atom: Anions/CationsNonmetals form anionsFor each negative charge, the ion has one more electron than the neutral atomF = 9 p+ and 9 e−, F− = 9 p+ and 10 e−P = 15 p+ and 15 e−, P3− = 15 p+ and 18 e−Anions are named by changing the ending of the name to -idefluorine F + 1e−  F−fluoride ionoxygen O + 2e−  O2− oxide ionMetals form cationsFor each positive charge, the ion has one less electron than the neutral atomNa atom = 11 p+ and 11 e−, Na+ ion = 11 p+ and 10 e−Ca atom = 20 p+ and 20 e−, Ca2+ ion = 20 p+ and 18 e−These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.Cations are named the same as the metalsodium Na  Na+ + 1e− sodium ioncalcium Ca  Ca2+ + 2e− calcium ionIV. Divisions/ Groups of the Periodic Table Metalsa. Good conductors of heat and electricityb. Malleable (can be pounded into flat sheets)c. Ductile (can be drawn into wires)d. Often shinye. Tend to lose electronsf. Examples : Chromium and Copper Nonmetalsg. Poor conductors of heat and electricityh. Tend to gain electronsi. Examples: Oxygen and Carbon Metalloidsj. Mixed propertiesk. Some are semiconductors (intermediate and temperature dependent electrical conductivity)l. Examples: Silicon and Germanium1. Group 8A elements (noble gases)Mostly unreactiveExamples: Helium and Neon2. Group 1A elements (alkali metals)Reactive metalsExamples: Sodium and Potassium3. Group 2A elements (alkaline earth metals)Reactive but not as reactive as Group 1AExamples: Magnesium and Barium4. Group 7A elements (halogens)Very reactive nonmetalsExample: Chlorine and BromineV. Isotopes: When Number of Neutrons Varies All isotopes of an element are chemically identical- undergo the exact same chemical reactions All isotopes of an element have the same number of protons Isotopes of an element have different masses Isotopes of an element have different numbers of neutrons Isotopes are identified by their mass numbers, which is the sum of all the protons and neutrons in the nucleusCurrent