Chapter 20 Metals

Properties of Metals The first metal used about 6,000 year ago was gold. The use of copper and silver followed a few thousands years later. In the periodic table, metals are elements found to the left of the stair-step line.

Metals usually have common properties – 1) they are good conductors of heat and electricity, and all but one are solid at room temperature.

Mercury Mercury is the ONLY metal that is not solid at room temperature. 2) Metals also reflect light. This property is called luster. 3) Metals are malleable. This means they can be hammered or rolled into sheets.

Properties of Metals 4) Metals area also ductile, which means they can be drawn into wires. These properties make metals suitable for use in objects ranging from eyeglass frames to computers to building structures.

Hey, How You Doing? Ionic Bonding in Metals. Metals generally have one to three electrons in their outer energy level or shell. (valence electrons) They tend to give up their electrons easily to a nonmetal.

Ionic Bonding When a metal atom bonds with a nonmetal atom, we call it an ionic bond. They want to combine so they may become stable. They want to take on the structure of a Nobel Gases.

Why do atoms combine? 1 Noble Gases Neon and the elements below it in Group 18 have eight electrons in their outer energy levels. Their energy levels are stable, so they do not combine easily with other elements.

Example: Magnesium Oxide: Draw the electron dot diagram first. Mg O

Example: Final Structure: Mg O

Metallic Bonding In metallic bonding, positively charged metallic ions are surrounded by a cloud of electrons. Metals are good conductors of electricity because the outer – level electrons are weakly held.

Breakdown Metals make up a majority of the periodic table. All the elements in Groups 1 – 12 are metal, as well as the elements under the stair-step line in group 13 – 15

Group 1 The Alkali Metals Li 6.941 11 Na 22.99 19 K 39.10 37 Rb 85.47 55 Cs 132.9 87 Fr (223)

Why do atoms combine? 1 Alkali Metals

Characteristics of Group 1 They are softer than most other metals, and the most reactive of all metals. They react rapidly, sometimes violently with oxygen and water. Alkali metals don’t occur in nature in their elemental form and are stored in substances that are unreacitve such as oil.

Characteristics of Group 1 Each atom of an alkali metal has one electron in its outer energy level, aka, their valence electron. This electron is given up easily thus giving an alkali metal a positive (+) charge

Example: NaCl - Na Cl Na Cl KBr - K Br K Br

Final thoughts on the Alkali family A radioactive element is one in which the nucleus breaks down and gives off particles and energy. Francium, which is the last alkali metal, is extremely rare and radioactive.

Group 2 – The Alkaline Earth Metals 4 Be 9.012 12 Mg 24.31 20 Ca 40.08 38 Sr 87.62 56 Ba 137.3 88 Ra 226.0

Alkaline Info Each atom of an alkaline earth metal has two electrons in its outer energy level. These electrons are given up when an alkaline earth metal combine with a nonmetal. As a result, the alkaline earth metal becomes a positively charged ion in compounds.

Write this Down!!!!!! If an element gives away its outer electron it becomes Positive. If an element receives the outer electron it becomes Negative.

Colors of fireworks Brilliant white light: Magnesium Red Flashes: Strontium

Extras Calcium is seldom used as a free metal, but its compounds are needed for life. Barium is used to diagnose some digestive disorders because it absorbs X-ray radiation well. Patients swallow a barium pill. Next, an x-ray will be taken while the barium is going through the digestive track.

The doctors can see where the barium is and diagnose internal abnormalities in the body. Radium, the last element in group 2, is radioactive.