Chapter 8 Periodic Table of Properties

Review: Mendeleev’s Periodic Table

Periodic Law Recall from C7…Elements in the same group (vertical column) have the same number of valence electrons resulting in similar properties This idea can be used to predict physical properties of elements and called Periodic Trends!

Periodic Trends: Atomic Radius (size)

Trend in Atomic Radius Explained: Why does atomic radius decrease across a period? – Higher # = more protons = higher core charge Increased attraction between p+ & e- – e- pulled closer to nucleus = ???? Why does atomic radius increase down a group? – Valence electron shell  higher n = higher probability of finding e- further from nucleus = ???? – Shielding by core e- = less pull on valence e- = ????

Periodic Trends in Ionic (-) Radius

Periodic Trends in Ionic (+) Radius

Trend in Ion Size Explained: Cation (+) radii are smaller than atomic radii – Why? Lose of valence e- Results in lower n, resulting in stronger nuclear pull Anion (-) radii are larger than atomic radii – Why? Gain of e- Results in increased repulsion between e-

Can you explain the following?

Properties of Metals ¾ of all known elements Solid at room temp (NOT Mercury) Low IE = give up electrons Metallic bonds – Delocalization Malleable, ductile

Alkali Metals Alkali Metals Video React with not only water, but many other substances – Do not find in elemental state Sodium and potassium – Relatively abundant – nerve impulses Your body would not function correctly w/out these Ion imbalance effects

Alkaline earth metals Alkali and Alkaline Earth Metals Video Denser, harder, higher melting & boiling Less reactive – Still not found in elemental form Magnesium and calcium most abundant – Magnesium is the most important Alloys – Calcium most commonly CaCO 3 Seashells, limestone – Hard Water

Aluminum Earth’s crust Commercial production Aluminum Video

Transition Elements Reactivity In nature Hardness & melting/boiling points Color Magnetism LAB: Colorful Transition Metals

Uses of Transition Metals Copper – Coins – nickel and penny – *Electrical conductor – Water transport Silver – Photographic film Photographic film Alloys – Different properties (chemical and physical) than individual metals Increased strength, hardness Lower electrical and thermal conductivity Lower melting point

Properties of Alloys (Cont) Impurities (in this case, C) occupy the spaces between atoms This makes the alloy stronger because atoms cannot slide past each other Lower electrical conductivities result because impurities block the path of e- in the electron sea Lower melting points result due to imperfect crystalline structure Fe C

Metalloids Properties of both metals and nonmetals – Nonmetallic structure and chemical behavior – Luster – Conduct electricity Not as well as metals = semiconductors Silicon – Metallic luster, but diamond structure – Most common metalloid – Quartz

Metalloids as Semiconductors Remember: Silicon is poor conductor – Certain impurities increase conductivity As small as 1 : 1,000,000!! Called doped crystals – Impurities affect silicon in two ways N-type P-type – Junctions: n-type next to p-type

Nonmetals - Carbon Distribution Allotropes

Nonmetals – Nitrogen Family Natural occurrence Reactivity Nitrogen cycle N 2 + 8H+ + 8e ATP  2NH 3 + H ADP + 16 Pi 2 NO 3 − + 10 e − + 12 H + → N H 2 O

Nitrogen Family (cont) Phosphorus – White phosphorus Reactivity Physical properties toxicity – Red phosphorus Physical properties

Nonmetals – Oxygen Family Oxygen – Abundance – Reactivity – Cellular respiration – O 3 allotrope Sulfur – Abundance – Industrial

Nonmetals – Halogens and Noble Gases Diatomic Reactivity – Halogens Video Halogens Video

Nonmetals - Noble Gases Helium Neon Argon Krypton Xenon Radon