Families of Elements ***Pull out your Periodic Tables!

Families of Elements***Pull out your Periodic Tables! Chapter 4.3

How are elements classified? • Two main groups: Metals and Nonmetals • Third group that is often used as a branch off Nonmetals: Semiconductors (Metalloids)

What are the differences? • Metal an element that is shiny and conducts heat and electricity well • Nonmetal  an element that conducts heat and electricity poorly • Semiconductor an element or compound that conducts electric current better than an insulator but not as well as a conductor does

Let’s look more into metals… • Alkali metals • Elements from Group 1 on the Periodic Table (on the very left!) • Characteristics: soft, shiny, reacts violently with water • Very reactive because they have one valence electron • Combine with other elements to form compounds • Example: Na (sodium!!) • Combines with Cl to make table salt (NaCl) • “That’s salty!!” -Mr. Parker

Alkaline-Earth Metals • Elements from Group 2 on the Periodic Table (2nd column from the very left!) • Have 2 valence electrons—so still reactive and may lose 2 electrons to form positive ions with a +2 charge • Often combine with other elements to form compounds

Alkaline-Earth Metals • Examples: • Calcium: • Hard shell of sea animals • Limestone- Corals • Marble • Magnesium: • Lightest of all structural metals— used in some airplanes • Used in milk of magnesia (medicine)

Transition Metals • Located in Groups 3-12 of the Periodic Table • Much less reactive • Called “transition metals” because they transition to having properties similar to Group 2 elements to having properties of Group 13 elements • Examples: Gold, Silver, Copper, Iron, Mercury

Mercury • Unique because it is the only metal liquid at room temperature • Harmful because you can breathe in the vapors, which accumulate in your body…and are toxic!

Synthetic “Manmade” Elements • Includes all elements with atomic numbers greater than 92 • Made for many different reasons • Examples: • Technectium –can be used to diagnose cancer in soft tissues of the body • Promethium- in some “glow in the dark” paints • Americium—small amount found in smoke detectors

Nonmetals • Located on the right side of the Periodic Table (except for Hydrogen) • Include some elements in Groups 13-16, and all elements in Groups 17 and 18

Characteristics of Nonmetals • Generally will form negative ions by gaining electrons by combining with other elements • Nitrogen and oxygen are the most plentiful gases in the air • Examples: • Oxygen ion: Oxide: O-2 • Nitrogen ion: Nitride: N-3 • Sulfur ion: Sulfide: S-2 has a rotten smell

Carbon- A nonmetal • Why is carbon useful? • Found almost everywhere! • Examples: • As graphite (pencil lead)—pure form • As diamond –pure form • Combined with other elements as: • Glucose C6H12O6 • Gasoline C8H18

The Halogens • Elements found in Group 17 • A group of nonmetals that are very reactive! • Want to gain electron to fill outer energy levels! • Examples: • Chlorine in ion form: Chloride ion: Cl- • Combines with sodium (Na) to form NaCl • Iodine in ion form: Iodide ion: I- • Added to table salt to make “ionized salt” • Fluorine in ion form: Fluoride ion: F- • Used in many toothpastes to prevent tooth decay

Noble Gases • Elements located in Group 18 • They are “inert” (nonreactive) • Because they have a filled outer energy level • Therefore they do not need to combine with other elements and so can be found in nature as single atoms instead of as molecules • Examples: • Neon—used for bright colors • Helium—in blimps and balloons to help objects ‘float’ since He is less dense than air • Argon—used to fill light bulbs

Semiconductors • Also referred to as metalloids • Clustered towards the right side of the Periodic Table • Includes only 6 elements: boron, silicon, germanium, arsenic, antimony, and tellurium

Semiconductors • Although classified as nonmetals, each semiconductor has some properties of metals • Able to conduct heat and electricity under certain conditions • Examples: • Boron—added to steel to increase hardness and strength; used to make heat-resistant glass

Silicon- A Semiconductor • Accounts for 28% of the mass of Earth’s crust • Combines with oxygen to make silicon dioxide, SiO2 (sand!) • Silicon chips are the basic building blocks of computers

Families of Elements ***Pull out your Periodic Tables!