Mendeleev arranged the elements in order of increasing atomic mass in a periodic table. He noticed that elements with similar properties fell into recurring patterns, allowing him to predict properties of undiscovered elements. Later, Moseley arranged elements by atomic number, better reflecting their properties. The periodic table organizes elements into metals, nonmetals, and metalloids, which have characteristic physical and chemical properties depending on their group and period.

1. The Periodic Table

2. 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.

3. 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.

4. 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

5. 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.

6. 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!

7. 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.

8. 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.

9. •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

10. Periodic Table: Organization
•The table is organized into columns, rows, and blocks, which are
based on certain patterns of properties.

11. 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.

12. •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

13. •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

14. •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

15. •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

16. 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

17. •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

18. •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

19. •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

20. Li, Na, K, Rb, Cs, Fr
Metals: Group 1 - Alkali Metals

21. Metals: Group 1 - Alkali Metals

22. 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.

23. Be, Mg, Ca,
Sr, Ba, Ra
Metals: Group 2 - Alkaline Earth Metals

24. 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.

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

26. 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.

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

28. 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.

29. Metals: Group 3-12 - Transition Elements
•Some lanthanide and actinide series elements have valuable
properties.
•Lanthanide series elements are used to make strong magnets.

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

31. 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

32. Metals: Fireworks

33. •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.

34. •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

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

36. •With the exception of hydrogen, nonmetals are located on the
right side of the periodic table.
metal nonmetalmetalloid
Nonmetals: Properties

37. •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

38. •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

39. Nonmetals: Sodium reacting with the halogen chlorine

40. 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.

41. 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.

42. 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.

43. 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.

44. •Between the metals and the nonmetals on the periodic table are
the metalloids.
Metalloids: Properties

45. •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

46. •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

47. •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