Unit 1: Atoms, Elements, & Compounds Section 2.2: The Periodic Table and Chemical Properties

The Periodic Table The periodic table is a chart that organizes the elements according to their physical and chemical properties.

Elements of the Periodic Table Although there are many versions of the periodic table, most contain the following properties: Atomic number 22 Ti Titanium 47.9 Symbol Name Atomic mass

Periodic Table Properties – Atomic Number The number of protons in the nucleus. The number of electrons surrounding the nucleus. The number of protons equals the number of electrons giving the atom a neutral charge. Atomic numbers increase one by one through the periodic table. Q: The atomic number of calcium (Ca) is 20. What can you now say about a calcium atom?

Periodic Table Properties: Atomic Mass & Mass Number The average mass of the atoms of an element. Written as a decimal number and is measured in amu. Mass Number The number of protons and neutrons in an atom of an element. It can be approximated by rounding off the atomic mass. # of Neutrons = Mass Number – Atomic Number Q: How many protons, electrons, and neutrons does an atom of Titanium contain?

Practice Question – Complete the following chart by referring to the periodic table: Element Name Symbol Atomic # Mass # # protons # neutrons # electrons K 19 39 18 22 Ra 226 61 47 201 80 hydrogen

Organization of the Periodic Table Groups of Elements (p.51) All elements in the periodic table can be classified as either metals, n0n-metals, or metalloids.

Organization of the Periodic Table Groups of Elements (p.51) What are 3 physical properties of metals, non-metals, and metalloids? Metals Non-metals Metalloids

Organization of the Periodic Table Periods (p.52) The periodic table is divided into horizontal rows called periods. Periods: Horizontal rows Numbered 1 to 7 Q: What period is Nickel located? _____ Q: How many elements are in period 1? _____

Organization of the Periodic Table Chemical Family The periodic table is also divided into vertical columns called chemical families. Chemical Family Elements have similar physical and chemical properties. Numbered 1 to 18. There are 4 well-known chemical families: Alkali metals alkaline earth metals halogens noble gases

Organization of the Periodic Table Chemical Family – Alkali Metals Alkali Metals (Column 1) Li, Na, K, Rb, Cs, Fr Highly reactive The reactivity increases as you go down the group. Are soft and can be cut with a knife.

Organization of the Periodic Table Chemical Family – Alkaline Earth Metals Alkaline Earth Metals (Column 2) Be, Mg, Ca, Sr, Ba, Ra Fairly Reactive – will burn in air if heated Are often used in fireworks since they produce bright flames Strontium (Sr) - red fireworks Magnesium (Mg) reacting to flame

Organization of the Periodic Table Chemical Family – Halogens Halogens (Column 17) F, Cl, Br, I, At Non-metals Highly reactive Fluorine is the most reactive while Iodine is the least. Astatine is very rare (not much is known)

Organization of the Periodic Table Chemical Family – Noble Gases Noble Gases (Column 18) He, Ne, Ar, Kr, Xe, Rn The most stable and unreactive elements At room temperature, they are colourless, odourless gases. Neon and Argon – used in light fixtures Neon – glows in different colours

Organization of the Periodic Table Transition Metals Found in the center of the periodic table. These are NOT a chemical family since they are spread over many columns. They are grouped together because of the arrangement of their electrons (more on this later in the chapter…) Share many common physical properties (eg., malleable, ductile, conductive, etc.) Q: Do you know which 3 transition metals are magnetic?

Section 2.2 To review and test your knowledge of the periodic table, we will: Play Periodic Bingo! Complete some questions!! Note: You will be having a test on all the material in Unit 1 up to this point. That is, Ch 1 (Sections 1.1 to 1.3) and Ch2 (Sections 2.1 and 2.2)