Section 3: Metals

CHAPTER 3: ELEMENTS AND THE PERIODIC TABLE

METAL

• A class of elements characterized by physical properties that include shininess, malleability, ductility, and conductivity.

PHYSICAL PROPERTIES OF METALS

• Shininess

• Malleability – ability to be hammered or rolled into flat sheets and other shapes

• Ductility – ability to be pulled out, or drawn, into a long wire

• Conductivity – ability to transfer heat or electricity

• *some metals are magnetic (iron, cobalt, nickel)

• *most are solids at room temperature (except for mercury)

MALLEABILITY

DUCTILITY

CONDUCTIVITY

CHECKPOINT 1

• What property of metals allows them to be drawn into wires?

CHECKPOINT 1

• What property of metals allows them to be drawn into wires?

• Ductility

CHEMICAL PROPERTIES OF METALS

• Metals have a range of reactivities (ease and speed with which an element combines, or reacts with other elements); react by losing electrons to other atoms

• Sodium (Na) reacts very strongly when exposed to air or water

• Gold (Au) and platinum (Pt) have a lack of reactivity

• Iron (Fe) falls in the middle; corrodes to form rust when it comes into contact with oxygen (O)

• Corrosion – gradual wearing away of a metal element due to a chemical reaction

• The reactivity of metals tends to decrease as you move from left to right across the periodic table.

CHECKPOINT 2

• What is reactivity?

CHECKPOINT 2

• What is reactivity?• The ease and speed with which an element combines, or

reacts with other elements.

METALS IN THE PERIODIC TABLE

• Alkali metals

• Alkaline earth metals

• Transition metals

• (Metals in mixed groups)

• Lanthanides

• Actinides

ALKALI METALS

• Metals in Group 1, from lithium to francium.

• React with other elements by losing one electron.

• So reactive that they are never found as uncombined elements in nature.

• Some are shiny and so soft that you can cut them with a plastic knife.

• Examples

• Sodium (Na): found in large amounts in seawater and salt beds, important in body

• Potassium (K): important in body

• Lithium (Li): used in batteries and some medicines

ALKALINE EARTH METALS• Group 2 of the periodic table.• Fairly hard, gray-white, and good conductor of electricity.• React by losing two electrons.• Not as reactive as alkali metals, but still very reactive; not found

uncombined in nature• Examples• Magnesium (Mg): can be mixed with aluminum to make a

strong but light-weight material• Calcium (Ca): essential part of teeth and bones; helps muscles

work properly

TRANSITION METALS• Elements in Groups 3 through 12• Hard and shiny• Good conductors of electricity• Many form colorful compounds• Less reactive; may take many years to react (rust/corrode)• Examples• Iron (Fe): important in blood• Copper (Cu)• Nickel (Ni)• Silver (Ag)• Gold (Au)

METALS IN MIXED GROUPS

• Some elements in Groups 13 through 15 are metals (don’t fit into any other category)

• Not very reactive

• Examples

• Aluminum (Al): lightweight metal

• Tin (Sn): protects steel from corrosion in some cans of food

• Lead (Pb): once used in paints and water pipes; poisonous; now used in car batteries and weights for balancing tires

LANTHANIDES

• Top row of elements placed beneath the periodic table

• Soft, malleable, shiny, high conductivity

• Mixed with more common metals to make alloys (mixtures of a metal with at least one other element, usually another metal)

• Usually found together in nature; difficult to separate from one another because they all share very similar properties

ACTINIDES

• Bottom row of elements placed beneath the periodic table.

• Only thorium (Th) and uranium (U) occur naturally on Earth

• Uranium used to produce energy in nuclear power plants

• All others created artificially in laboratories

• Nuclei of these elements are very unstable, meaning that they break apart very quickly into smaller nuclei

• Some only exist for fraction of a second

EXTENDED PERIODIC TABLE

CHECKPOINT 3

• What happens to reactivity as you move from left to right across the periodic table?

CHECKPOINT 3

• What happens to reactivity as you move from left to right across the periodic table?

• It decreases.

SYNTHETIC ELEMENTS

• Elements with atomic numbers higher than 92 (after uranium) do not occur naturally on Earth; they are made – or synthesized – when nuclear particles are forced to crash into one another.

• Examples

• Plutonium is made by bombarding nuclei of uranium-238 with neutrons in a nuclear reactor.

• Americium-241 is made by bombarding plutonium nuclei with neutrons

• Particle accelerator: powerful machines that move atomic nuclei faster and faster until they crash into one another, sometimes forming heavier elements

• Gets more difficult as atomic number increases

• New elements given temporary three-letter names

CHECKPOINT 4

• What is a synthetic element?

CHECKPOINT 4

• What is a synthetic element?

• An element that does not occur in nature. They are made in laboratories, sometimes using particle accelerators. They are heavier than uranium.

POST-LESSON QUIZ

1. Which is not a property of metals?

a. shininess

b. ductility

c. malleability

d. poor conductivity

POST-LESSON QUIZ

2. Which metals are the most reactive?

a. alkaline earth metals

b. alkali metals

c. transition metals

d. lanthanides

POST-LESSON QUIZ

3. What tells us the ease and speed with which an element combines with other elements?

a. reactivity

b. ductility

c. conductivity

d. malleability

POST-LESSON QUIZ

4. Which category of metals is found in Group 2?

a. alkali metals

b. transition metals

c. alkaline earth metals

d. actinides

POST-LESSON QUIZ

5. What does it mean for an element to be “synthesized”?

a. it is on the left side of the periodic table

b. it is lightweight

c. it is made in laboratories

d. it is found in nature