Hydrogen Most common isotope has 1 proton and no neutrons, making Hydrogen (H) the lightest element Most abundant element in the universe (~75% of baryonic matter) In stars, atoms of Hydrogen (H) fuse together to create atoms of Helium (He) 1 Hydrogen is very important in acid-base chemistry as it can gain or lose an electron. It is also, with carbon, a component of all organic compounds. On your periodic table, highlight Hydrogen in pink. After the Big Bang, most of the atoms formed were hydrogen. Why is hydrogen so much more abundant than any other element?

Helium 2 nd lightest element & 2 nd most abundant element in the universe (~24% of total baryonic matter). Large amounts being produced by stars Relatively inert (does not react) Helium is used for superconductors, cryogenics, and buoyancy. Despite its abundance in the universe, very little helium occurs in Earth’s atmosphere. What helium there is, has been produced by the radioactive decay of heavy elements. On your periodic table, highlight Helium in blue. 2

Oxygen 8 6 valence electrons Highly reactive non-metal oxidizing agent Forms molecules with most elements By mass, 3 rd most abundant element in universe Necessary to most terrestrial life but so chemically reactive that it must be constantly replenished by photosynthesis. (Photosynthesis obtains oxygen from water). On your periodic table, circle Oxygen in red

Iron 26 Can have several different electron configurations (number of electrons in outside orbital) As the decay product of the last nuclear reaction in high-mass stars, iron is common in all rocky planets. It is the most common element in Earth, 4 th most common in the crust Metal that reacts with oxygen (O) to form minerals of iron oxide (Fe 2 O 3, FeO) Iron is an incredibly important metal. It is the primary component of steel, which is a metal alloy. Iron is also part of the molecular complex hemoglobin, the oxygen transporter for most aerobic organisms. On your periodic table, highlight Iron in orange.

Alkali Metals Group 1 – Alkali Metals 1 valence electron – lose an electron highly reactive React strongly with water to produce a strong base and hydrogen gas Soft metals with low densities The alkali metals were not produced in large numbers during the Big Bang, so they are relatively rare. Valuable minerals including alkali metals include the halides. On your periodic table, circle the alkali metal group in green. Label the group ‘Alkali Metals’ Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), Francium (Fr)

Alkaline Earth Metals Group 2 – Alkaline Earth Metals 2 valence electrons – lose 2 electrons somewhat reactive Not as reactive as the Alkali Metals Soft metals with low densities The alkaline earth metals are abundant in Earth’s crust, particularly Magnesium (Mg) and Calcium (Ca). These elements are primary components of many minerals in earth’s crust and in soil. On your periodic table, circle the group using purple. Highlight magnesium and calcium in purple. Label the group ‘Alkaline Earth Metals’. Beryllium (Be), Magnesium (Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), Radium (Ra)

Metals Groups Solids Have shiny surfaces Good conductors of heat & electricity Tend to bend easily when in thin sheets (malleable) Many metals are valuable natural resources. Gold (Au), Silver (Ag), and Copper (Cu) are native elements and can exist in Earth’s crust as nuggets of pure metal. These metals are all mined in the state of Nevada. On your periodic table, color Gold (Au), Silver (Ag), and Copper (Cu) yellow. Look at your periodic table, from the atomic perspective, why would Cu, Ag, and Au all exist in the native form while other metals do not?

Halogens Group 17 = Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine, & Astatine 7 valence electrons – Gain an electron. Highly reactive Fluorine, the most reactive, will even react with the noble gases. In Earth’s crust, bond with sodium (Na), potassium (K), or calcium (Ca) to form mineral compounds called halides The halogens are incredibly toxic and reactive but this also makes them useful. Chlorine (Cl) and Bromine (Br) are important disinfectants. Hydrochloric acid has numerous industrial uses including the production of PVC plastic. On your periodic table, circle the halogen group in green. Label the group ‘Halogens’ How could atomic mass explain the decreasing reactivity of the halogens down the group?

Noble Gases Group 18 = Helium (He), Neon (Ne), Argon (Ar), Krypton, Xenon, Radon 8 valence electrons - ‘full’ outer energy levels Very low reactivity (inert) The noble gases have very low boiling points meaning that compressing one creates a liquid at very low temperature. This property is used in cryogenic freezing. On your periodic table, circle the noble gas group in blue. Label the group ‘Noble Gases’

Radioactive Elements Have unstable nuclei Over time, nuclei of these elements decay into stable daughter nuclei by releasing particles and energy. For example, uranium-238 decays into lead-206. The rate of radioactive decay is constant Uranium-238, Thorium-232 Radioactive elements are used in smoke detectors, as medical detectors, as tracers of other chemicals, and to date the age of rocks. On your periodic table, highlight Uranium in green. Draw an arrow from Uranium (U) to its daughter, lead (Pb). (The atomic number of lead is 82)

Other Important Elements On your periodic table, find and circle, in black, each of the following elements 1.Aluminum (Al) 2.Carbon (C) 3.Lead (Pb) 4.Nickel (Ni) 5.Nitrogen (N) 6.Silicon (Si)