Periodic Table

And the Periodic Law

Dmitri Mendeleev

• Russian chemist• Created a table by arranging elements

according to atomic masses• Noticed that chemical properties of the

elements followed a repeating pattern

Periodic Law

– Henry Moseley who worked with Ernest Rutherford was the scientist who improved on Mendeleev’s periodic table by ordering the elements by the number of protons – the atomic number.

• The physical and chemical properties of the elements are periodic functions of their atomic numbers.

Mendeleev left spaces in his periodic table and predicted the

existence of 3 elements and their

1. Atomic numbers2. Colors3. Properties4. Radioactivity

Arrangement of the table

• The periodic table is an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column or group.

Groups of the Periodic Table

• 1st column (gold) alkali metals

• 2nd column (purple) alkaline earth metals

• 3rd-12th Transition Metals

• 17th column – halogens

• 18th – Noble Gases

Electron Configuration and the Periodic Table

• The periodic table can be divided into blocks which indicate which orbitals are filling.

s Block – Groups 1and 2

• All are chemically reactive metals• Metals in group 1 (alkali metals) are more

reactive than metals in group 2 (alkaline earth metals)

• Neither are found in nature as elements since they react readily with water and nonmetals.

Which is more reactive, magnesium or sodium?

1. Magnesium (Mg)2. Sodium (Na)

Name the element [Ar] 4s2

1. Sodium2. Potassium3. Calcium4. Strontium

Alkali Metals Video

Hydrogen and Helium

• Hydrogen is not an alkali metal.• Hydrogen is a unique element.

• Helium is placed with the noble gases• Helium has a full outer shell of electrons.• Helium is a colorless gas, not a reactive

metal.

d Block – Groups 3-12

• Some of these elements don’t follow the diagonal rule exactly in electron distribution

• Metals with typical metallic properties.– Good conductors of electricity– High luster

• Called the transition elements.• Less reactive than s block metals

Name the element [Ar]4s23d5

1. Bromine2. Iron3. Magnesium4. Manganese

p block – groups 13 – 18except helium

• p block and s block together are called the main group elements

• Properties of this group vary– On the right side – nonmetals– On the left – metals– In between – metalloids (boron, silicon,

germanium, arsenic, antimony, tellurium)

Metals, Nonmetals, Metalloids

• Metal- element that is shiny and malleable, and conducts heat and electricity

• Nonmetal – Conducts heat and electricity poorly and is brittle

• Metalloid – Element that has the properties of both metals and nonmetals, sometimes called a semiconductor

An element which is shiny and brittle is likely a

1. Metal2. Nonmetal3. Metalloid4. s-block element

p-block

• Group 17 – Halogens (fluorine, chlorine, bromine, iodine, astatine)– Most reactive nonmetals

• Group 18 – Noble Gases (helium, neon, argon, krypton, xenon, radon)– Nonreactive and stable

f-block: Lanthanides and Actinides

• Lanthanides are shiny metals, with reactivity similar to the alkaline earth metals

• Actinides are all radioactive, many are man-made

Name the group

1. Alkali metals2. Alkaline earth

metals3. Halogens4. Noble Gases

Name the group

1. Alkali metals2. Alkaline earth

metals3. Halogens4. Noble gases

Name the section of the table

1. S block2. P block3. D block4. F block

What types of elements make up the p block?

1. Metals2. Nonmetals3. Metalloids4. All of the above

Periodic Trends

• The arrangement of the periodic table shows directional trends for various properties of the atoms of each element.

Nuclear Charge and Atomic Radius

• Atoms decrease in size from left to right on the periodic table because of the increase in nuclear charge.

IN A ROW IN THE PERIODIC TABLE, AS THE ATOMIC NUMBER INCREASES, THE

ATOMIC RADIUS1. Decreases2. Remains constant3. Increases4. Becomes

immeasurable

Within a group of elements,as the atomic number increases, the

atomic radius1. Increases2. Remains constant3. Decreases4. Varies

unpredictably

Ionization Energy

• The energy required to remove an electron from a neutral atom of an element.– A large ionization

energy shows that the electrons of an atom are bound more tightly to the nucleus and it is more difficult to remove the electron.

Which group of elements has the highest ionization energies?

1. Alkali metals2. Halogens3. Noble gases4. Alkaline earth

metals

The energy required to remove an electron from an atom is called the

1. Electron affinity2. Electron energy3. Electronegativity4. Ionization energy

Ionization Energy (IE) Trends

• IE generally increases across each period.– As the nuclear charge increases, the

electrons are held more tightly

• IE decreases down a group– As the electrons reside farther from the

nucleus, they can be removed more easily.

Valence Electrons

• The electrons available to be lost, gained, or shared in the formation of chemical compounds are referred to as the valence electrons.

• Valence electrons are those filling s and p orbitals.

Valence electrons are those s and p electrons

1. Closest to the nucleus

2. In the lowest energy level

3. In the highest energy level

4. Combined with protons

The number of valence electrons in Group 17 elements is

1. 72. 83. 174. Equal to the

period number

The electrons available to be lost, gained or shared when atoms form

compounds are called

1. Ions2. Valence electrons3. d electrons4. Electron clouds

Electronegativity

• A measure of the ability of an atom in a chemical compound to attract electrons from another atom in the compound.

Fluorine is assigned a value of 4 and all other elements have values relative to it.

The element that has the greatest electronegativity is

1. Oxygen2. Sodium3. Chlorine4. Fluorine

Higher Electronegativity

Smaller atoms have higher electronegativity. Higher coulombic attraction extends to electrons

of other atoms that are involved in a covalent bond.

Noble GasesThere is no value for

electronegativity of noble gases, since they are not generally

involved in bonding.