Ch 10 The Periodic Table

10.1 Using the Periodic Table Discovering a Pattern Dmitri Mendeleev discovered a pattern to the elements in 1896. First he wrote the names and properties of the elements on cards. Then he arranged his cards in order of increasing mass. A pattern appeared!  Periodic - happening at regular intervals like days of the week.

10.1 Using the Periodic Table Elements with similar properties occurred in a repeating pattern.

10.1 Using the Periodic Table Discovering a Pattern Mendeleev predicted that elements yet to be found would fill in the gaps in his table. He was right! Missing element Germanium (Ge) fit into his gap.

10.1 Using the Periodic Table Changing the Arrangement Some elements did not fit in the table by increasing atomic mass – so Mendeleev changed his table. 1914 Henry Moseley determined the number of protons in an element. When the periodic table was arranged by increasing atomic number, all elements fit the table. Periodic Law-states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements

10.1 Using the Periodic Table Decoding the Periodic Table Each square on the periodic table includes: Atomic number Chemical symbol Chemical name atomic mass

10.1 Using the Periodic Table Decoding the Periodic Table Period- Each horizontal row of elements Group- Each column of elements. Elements in the same group have similar properties. Elements in the same period have the same number of electron shells

10.2 Metals The Periodic Table and Classes of Elements We break elements into three major groups Metals Nonmetals Metalloids

10.2 Metals Metals – found to the left of the zigzag line Few electrons in the outer energy level All solids at room temp. except Mercury (Hg) Lustrous ductile malleable good conductors

10.2 Metals Properties of metals Luster - describes the ability of a metal to reflect light Malleability - describes the ability of a substance to be hammered or rolled into sheets Ductility- describes the ability of a substance to be pulled into thin wires Good conductors of electricity and thermal energy Higher densities, boiling points, and melting points in general

10.2 Metals Alkali Metals Group: 1 Valence Electrons: 1 Valence electron - electron in the highest occupied energy level Reactivity : Very reactive can easily give away the 1 electron Often stored in oil because they react violently with water and oxygen Soft, silver color, shiny and low density

10.2 Metals Alkali metals in water

10.2 Metals Alkaline Earth Metals Group: 2 Valence Electrons: 2 Reactivity: reactive but less than alkali metals silver color, higher density

10.2 Metals Chlorophyll contains Mg; oyster shell, pearl, and cast contain calcium

10.2 Metals Transition Metals Group: 3-12 Valence Electrons: varies (1 or 2) Reactivity: much less reactive Shiny, good conductors, higher densities and melting points (except Hg) Some transition metals from periods 6 & 7 appear below the table to save space. Elements in each row tend to have similar properties Lanthanides- shiny, reactive metals Actinides- radioactive , or unstable. Elements listed after plutonium do not occur naturally.

10.3 Nonmetals and metalloids Nonmetals - found to the right of the zigzag line almost a complete outer energy level (Group 18 is complete) more than half are gases at room temp. not shiny not malleable not ductile not good conductors (good insulators)

10.3 Nonmetals and metalloids Metalloids – found on the zigzag outer energy level is half full have some properties of metals have some properties of nonmetals sometimes called semiconductors Semiconductors conduct electricity at high temperatures but not at low temperatures

10.3 Nonmetals and metalloids Boron Group Group: 13 Valence Electrons: 3 Reactivity: reactive 4 metals, 1 metalloid solid at room temp. Aluminum (Al) is most abundant metal in Earth’s crust

10.3 Nonmetals and metalloids

10.3 Nonmetals and metalloids Carbon Group Group: 14 Valence Electrons: 4 Reactivity: varies solids at room temp. carbon is nature’s most important element. Found in carbohydrates, proteins, fats, and nucleic acid (DNA) Germanium and silicon are used as conductors in computer chips

10.3 Nonmetals and metalloids

10.3 Nonmetals and metalloids Nitrogen Group Group: 15 Valence Electrons: 5 Reactivity: varies most are solids at room temp. except N N is 80% of the air we breathe, fertilizer

10.3 Nonmetals and metalloids

10.3 Nonmetals and metalloids Oxygen Group Group: 16 Valence Electrons: 6 Reactivity: very reactive Oxygen (O) is 20% air and needed for substances to burn

10.3 Nonmetals and metalloids

10.3 Nonmetals and metalloids Halogens Group: 17 Valence electrons: 7 Reactivity: very reactive – most reactive nonmetals Form salts with alkali metals poor conductors

10.3 Nonmetals and metalloids

10.3 Nonmetals and metalloids Noble Gases Group: 18 Valence electrons: 8 (except He – 2) Reactivity: unreactive Colorless, odorless gases at room temp.

10.3 Nonmetals and metalloids

10.3 Nonmetals and metalloids Hydrogen Group: 1 - in group 1 only due to valence electrons (does not share any other properties with the alkali metals) Valence electrons: 1 Reactivity: very reactive colorless, odorless, explosive reactions w/ oxygen