The Periodic Table

What do you think? Agree or Disagree•The elements on the periodic table are arranged in rows in order

they were discovered. •The properties of an element are related to the elements location

on the periodic table.•Fewer than half of the elements are metals. •Metals are usually good conductors of electricity. •Most of the elements in living things are nonmetals. •Even though they look very different, oxygen and sulfur share

some similar properties.

Mendeleev: Developing a Periodic Table

• In 1869 a Russian chemist, inventor and teacher names Dimitri Mendeleev. formulated the Periodic Law. He used it to correct the properties of some already discovered elements and also to predict the properties of elements yet to be discovered.

Mendeleev: Developing a Periodic Table

•Mendeleev studied the physical properties such as density, colour, melting point and atomic mass of each element.

•Mendeleev also studied chemical properties such as how each element reacted with other elements.

•He arranged the elements in a list using their atomic masses. •He noticed that the properties of the elements seemed to repeat

in a pattern. •When Mendeleev placed his list of elements into a table, he

arranged them in rows of increasing atomic mass. Elements with similar properties were grouped in the same columns

Periodic Table: Patterns in Properties•Mendeleev noticed that melting point is one property that shows

a repeating pattern.

•Boiling point and reactivity also follow a periodic pattern.

Periodic Table: Predicting Properties

•When Mendeleev arranged the elements by increasing atomic mass, there were large gaps between some elements.

•He predicted that scientists would discover elements that would fit into these spaces.

•He also predicted that the properties of these elements would be similar to the known elements in the same column.

•He was right! Both predictions turned out to be true!

Periodic Table: Predicting Properties

•Mendeleev believed that the atomic masses of certain elements must be invalid because the elements appeared in the wrong place on the periodic table.

•He placed elements whose properties resembled each other’s closer together in the table.

Periodic Table: Predicting Properties

•In the early 1900’s Henry Moseley solved the problem!

•When Moseley listed the elements according to atomic number, columns contained elements with similar properties, such as copper, silver, and gold.

•Even today, new elements are created in laboratories, named, and added to the present-day periodic table.

•These elements are all synthetic and do not occur naturally on Earth.

•Scientists can use the periodic table to predict the properties of new elements they create.

Periodic Table: New Elements

Periodic Table: Organization•The table is organized into columns, rows, and blocks, which are

based on certain patterns of properties.

Periodic Table: Element Key •The element key shows an element’s chemical symbol, atomic

number, and atomic mass.•The key also contains a symbol that shows the state of matter at

room temperature.

•A group is a column on the periodic table.•Elements in the same group have similar chemical properties and

react with other elements in similar ways.•There are patterns in the physical properties of a group such as

density, melting point, and boiling point.

•The groups are numbered 1-18.

Periodic Table: Groups

•The rows on the periodic table are called periods.•The atomic number of each element increases by one as you read

from left to right across each period.•The physical and chemical properties also change as you move

left to right across a period.

Periodic Table: Periods

•Almost 3/4 of the elements on the periodic table are metals. •Metals are on the left side and in the middle of the periodic

table.

Metals: Properties

metal nonmetalmetalloid

•Luster describes the ability of a metal to reflect light. •Gold has good luster and that is why people use it for jewelry. •Gold also conducts electricity, but is too expensive to use in

normal electrical wires. Cooper is often used. •Ductility is the ability to be pulled into thin wires. •A piece of gold with the mass of a paper clip can be pulled into a

wire that is more than 3 km long!

Metals: Physical Properties

3 km

An ounce of pure gold the size of a matchbox can be flattened into a sheet the size of a tennis court.

•Malleability is the ability of a substance to be hammered or rolled into sheets.

Metals: Physical Properties

•Density, strength, boiling point, and melting point of a metal are greater than those of other elements.

•Except for mercury, all metals are solid at room temperature.

Metals: Physical Properties

•A chemical property is the ability or inability of a substance to change into one or more new substances.

•The chemical properties of metals can differ greatly. •However, metals in the same group usually have similar chemical

properties. •For example, gold and other elements in group 11 do not easily

react with other substances.

Metals: Chemical Properties

•The elements in group 1 are called alkali metals. •Alkali metals have similar chemical properties. •They react quickly with other elements, such as oxygen. •Because of this, in nature they only occur in compounds. •Alkali metals have similar physical properties. They have a silvery

appearance. •They are soft enough to be cut with a knife. •They have the lowest densities of all metals.

Metals: Group 1 - Alkali Metals

Li, Na, K, Rb, Cs, Fr

Metals: Group 1 - Alkali Metals

Metals: Group 1 - Alkali Metals

Metals: Group 2 - Alkaline Earth Metals

•The elements in group 2 are called alkaline earth metals. •Alkaline earth metals also react quickly with other elements, but

not as quickly as alkali metals. •Pure alkaline earth metals do not occur naturally. Instead they

combine with other elements to form compounds.

Be, Mg, Ca, Sr, Ba, Ra

Metals: Group 2 - Alkaline Earth Metals

Metals: Group 3-12 - Transition Elements •Groups 3-12 are called transition elements. •Transition elements are in a block at the center and two rows at

the bottom of the periodic table.

Metals: Group 3-12 - Transition Elements •Many colorful materials contain small amounts of transition elements.

Metals: Group 3-12 - Transition Elements

•All transition elements are metals with higher melting points, greater strength, and higher densities than the alkali metals and the alkaline earth metals.

•Transition elements also react less quickly with oxygen. •Some can occur in nature as free elements, meaning that it is pure

form, it is not within a compound. •Because of their high densities, strength, and resistance to corrosion,

transition elements make good building materials.

Metals: Group 3-12 - Transition Elements •Name one everyday use of a transitional element.

Metals: Group 3-12 - Transition Elements •Two rows of transition elements—the lanthanide and actinide

series—were removed from the main part of the table so that periods 6 and 7 were not longer than the other periods.

Metals: Group 3-12 - Transition Elements •Some lanthanide and actinide series elements have valuable

properties. •Lanthanide series elements are used to make strong magnets.

Metals: Patterns in Properties •Metallic properties include luster, malleability, and electrical conductivity.

Metals: Fireworks

blue: copper compounds

yellow: sodium compounds

white-hot: barium-oxygen compounds or aluminum

or magnesium burn green: barium compounds

orange: calcium

compounds

red: strontium and lithium compounds

gold: iron burned with

carbon

purple: mix of strontium and copper compounds

Metals: Fireworks

•More than 96 percent of the mass of the human body comes from four nonmetals–oxygen, carbon, hydrogen, and nitrogen.

Nonmetals

•Nonmetals are elements that have no metallic properties.

•The four elements that make up most of the human body, along with phosphorus and sulfur, are the six elements in proteins, fats, nucleic acids, and other large molecules in your body and in all other living things.

•solid at room temperature (except mercury)

•have luster•good conductors of electricity

and thermal energy•ductile, malleable

Nonmetals: Comparison

•many are gases at room temperature

•those that are solid have a dull surface, therefore no luster

•poor conductors of electricity and thermal energy, therefore good insulators

Metals Nonmetals

•Phosphorus and carbon are dull, brittle solids that do not conduct thermal energy or electricity.

Nonmetals: Properties

•With the exception of hydrogen, nonmetals are located on the right side of the periodic table.

metal nonmetalmetalloid

Nonmetals: Properties

•Groups 14-16 contain metals, nonmetals, and metalloids.

•The chemical properties of the elements in each group are similar.

•The physical properties are quite different.

Nonmetals: Group 14-16

•The term halogen refers to an element that can react with a metal and form a salt.

•For example chlorine gas reacts with solid sodium and forms sodium chloride (NaCl).

Nonmetals: Group 17: The Halogens

Nonmetals: Sodium reacting with the halogen chlorine

Nonmetals: Group 17: The Halogens •Halogens react so readily that they can only occur

naturally in compounds. They do not exist as free elements.

•They even form compounds with other nonmetals, such as carbon.

•Halogens are less reactive as you move down the group.

Nonmetals: Group 18: The Noble Gases •The elements in group 18 are known as the noble gases.•Unlike the halogens, the only way elements in this group

react with other elements is under special conditions in a laboratory.

•Of all the elements, hydrogen has the smallest atomic mass and is the most common element in the universe.

Nonmetals: Group 18: The Noble Gases

•These elements were not discovered when Mendeleev constructed his periodic table because they do not form compounds naturally.

•Once they were discovered they fit into a group at the far right of the table.

Nonmetals: Hydrogen •Hydrogen is most often classified as a nonmetal because it has many

properties like those of nonmetals.•However, hydrogen also has some properties similar to those of the

group 1 alkali metals.•Under conditions on Earth, hydrogen usually behaves as a

nonmetal.

•Between the metals and the nonmetals on the periodic table are the metalloids.

Metalloids: Properties

•A metalloid is an element that has physical and chemical properties of both metals and nonmetals.

•Silicon is the most abundant metalloid in the universe.

Metalloids: Properties

•Remember that metals are good conductors of electricity and thermal energy. Nonmetals are poor conductors.

•A property of metalloids is the ability to act as a semiconductor.•A semiconductor conducts electricity at high temperatures, but not at

low temperatures.

•At high temperatures metalloids act like metals and conduct electricity.

•At lower temperatures metalloids act like nonmetals and stop electricity from flowing.

•This property is useful in electronic devices such as computers, tv’s and solar cells.

Metalloids: Properties

•An element’s position on the periodic table tells you a lot about the element.

•Understanding the properties of elements can help you decide which element to use in a given situation.

Metalloids: Properties