Chapter 5 The Periodic Table

“repeated in a pattern.” Definition: Periodic means “repeated in a pattern.” Elements are organized in the periodic table by increasing atomic number.

History of the Periodic Table In the 1869, a Russian chemist named Dimitri Mendeleev, devised the first periodic table.

History of the Periodic Table Mendeleev’s table was based on mass number - the combined mass of both protons and neutrons

Improving the Periodic Table In 1913, a young English scientist named Henry Moseley arranged the elements by atomic number rather than atomic mass.

Improving the Periodic Table The atomic number is the number of protons in the nucleus.

Periodic law When elements are arranged by atomic number they have chemical and physical properties that appear at regular intervals. This is known as the “periodic law”

Understanding the Periodic Table Periods are horizontal rows of elements that contain increasing numbers of protons and electrons

Understanding the Periodic Table Vertical columns in the periodic table are called groups or families and are numbered 1 through 18. Elements in each group have similar properties.

Energy Levels The reason that elements in the same group have the properties is because they have the same number of electrons in their outer energy level (valence)

Periodic Trends Group # = elements in same group have same # of valence electrons Families have similar reactivity. 1A 2A 3A 4A 5A 6A 7A 8A

Periodic Trends (Color/highlight one group pink. Number the columns 1-18 above the periodic table) 1A 2A 3A 4A 5A 6A 7A 8A

Periodic Trends Period # = # of energy levels (Color/highlight one period green. Number the periods 1-7 on the left side of the periodic table.)

Columns & Rows Group (Family) Period

Ion formation If an atom gains or loses electrons, it no longer has an equal number of electrons and protons. The atom has a net electric charge. It is an ion.

Ion formation Group 1 elements form positive ions (cation). – The single valence electron is easily removed. Group 17 elements form negative ions (anion). – The addition of one valence electron fills the outer energy level

How are Elements Classified? Elements in each category metals nonmetals Metalloids will have similar properties.

How are Elements Classified? metal: an element that is shiny and that conducts heat and electricity well nonmetal: an element conducts heat and electricity poorly. Solids are dull and brittle.

How are Elements Classified? 3. metalloid: elements that can form ionic and covalent bonds with other elements and can have metallic and nonmetallic properties

How are Elements Classified?

Metals hard, shiny, all but one Mercury, are solid at room temperature. Good conductor of heat and electricity

Metals Luster - reflects light well Malleable - can be hammered into a thin sheet Ductile - can be drawn into wires

Alkali Metals (group 1) other metals one valence electron shiny, malleable, ductile, softer than other metals one valence electron Includes sodium, a soft and shiny metal that reacts violently with water.

Alkali Metals (group 1) are the most reactive metals found in nature only as compounds. All living things need K and Na to stay healthy.

Alkali metals

Alkaline Earth Metals (group 2) shiny, malleable, ductile, reactive metals two valence electrons harder, denser, stronger, and have higher melting points than alkali metals. Application/Uses: Magnesium in vehicles and baseball bats, Strontium in fireworks, Calcium for bones, Barium for disease diagnoses.

Alkaline Earth metals

Transition metals

Transition elements (groups 3 - 12) harder, more dense, and have higher melting points than alkali metals and alkaline-earth metals. They are less reactive and are often occur in nature uncombined form colored compounds (Co, Cr, Cd) They are responsible for the beautiful colors of gems.

Transition elements (groups 3 - 12) The iron triad consists of iron, cobalt, & nickel. These are used to create steel & other metal mixtures. Iron is the most widely used of all metals and is the 2nd most abundant metallic element in the Earth’s crust.

Transition elements (groups 3 - 12) Copper – ductile, conducts electricity

Transition elements (groups 3 - 12) The coinage metals are copper, gold and silver. Zinc is often used to plate other metals.

Transition elements (groups 3 - 12) The inner transition metals are disconnected from the rest of the periodic table. They are the Lanthanides (1st row – atomic # 58-71) and Actinides (2nd row – Atomic # 90-103).

Synthetic elements Man-made elements created in the laboratory are called synthetic elements. All elements with an atomic number greater than 92 are synthetic and radioactive. They are called Transuranium elements.

Nonmetals Usually they are gases at room temperature. Some are solids and one, Bromine is a liquid. They have opposite properties from metals: dull, brittle, powdery, poor conductors of heat and electricity. found on the right side of the periodic table (except for hydrogen) includes Hydrogen, some elements in Groups 13–16, and all of the elements in Groups 17 and 18.

Diatomic molecules – Two atoms of the same element bonded *Diatomic molecules – Two atoms of the same element bonded. Cannot be found in nature by themselves. 7 of these: H2 N2 O2 F2 Cl 2 Br2 I2

Nonmetals Noble Gases - Group 18 are very stable due to a full outer energy level, which means they are nonreactive. They have 8 valence electrons. They are useful in lights, blimps, and weather balloons. Includes Helium, Neon, and Argon

Nonmetals

Halogens (group 17) Halogens - Group 17 have 7 valence electrons. Most reactive of nonmetals combine easily with metals to form salts They are also useful as disinfectants. Includes chlorine and iodine

Nonmetals

Other Nonmetals

Hydrogen Hydrogen is the only nonmetal in group one. It is diatomic. It is highly reactive. It is highly reactive because it has only one electron that can easily be lost to form a bond. 1 valance electron Most abundant element in universe Combines with oxygen to form water

Metalloids can form ionic and covalent bonds, can have both metallic and nonmetallic properties. located along the stair-step line on the periodic table. Six elements: boron, silicon, germanium, arsenic, antimony, tellurium able to conduct heat and electricity under certain conditions.  

Semiconductorsor Metalloids

Mixed Groups The mixed groups - Groups 13 -16 contain metals, nonmetals, and metalloids/semiconductors.

Mixed Groups Group 13 is called the Boron group. Aluminum is very abundant in the earth’s crust and has many uses such as cans and aircraft.

Mixed Groups Group 14 is called the Carbon group. Allotropes – different forms of the same element having different molecular structures. Allotropes of carbon are: 1. graphite - black powder (pencil lead), 2. diamonds - clear crystals.

Mixed Groups Group 15 is the Nitrogen group. Group 16 is the Oxygen group. Oxygen makes up 20% of the air as O2. As O3, it protects us from the sun’s radiation.

Elements become less metallic across each period.