The Modern Periodic Table

Chapter 5.2

Most often there are 4 pieces of information

for each element listed on the periodic table.

Element Information in the Periodic Table

Most often there are 4 pieces of information

for each element listed on the periodic table.

Element Information in the Periodic Table

Atomic number(# of protons)

Most often there are 4 pieces of information

for each element listed on the periodic table.

Element Information in the Periodic Table

Atomic number

Element symbol(1st capital, 2nd small)

Most often there are 4 pieces of information

for each element listed on the periodic table.

Element Information in the Periodic Table

Atomic number

Element symbol

Element name

Most often there are 4 pieces of information

for each element listed on the periodic table.

Element Information in the Periodic Table

Atomic number

Element symbol

Element name

Atomic mass

Atomic mass depends on:

Distribution of an element’s isotopes Masses of those isotopes.

Isotopes = same element, different masses Masses different because:

Same # protons Different # neutrons

Atomic Mass

Atomic Mass Units

Scientists chose one isotope to serve as a standard.

This isotope is the most abundant one found in nature Carbon-12 atom: 6 protons and 6 neutrons.

1 Atomic Mass Unit (amu) = one twelfth the mass of a carbon-

12 atom.

Atomic Mass

Most elements are mixtures of 2 or

more isotopes. Atomic mass is weighted average.

Example: Chlorine atomic mass = 35.453 amu. Two natural isotopes of chlorine: chlorine-

35; chlorine-37 Chlorine-35: 17 protons and 18 neutrons. Chlorine-37: 17 protons and 20 neutrons.

Elements in modern periodic table arranged

by increasing atomic number (not mass) (Atomic number = # of protons).

Periodic Law - Pattern of Repeating Properties Periods - Each row is a period.

Each period is for a different electron shell or energy level

The Periodic Law

All of the Electron Shells

Modern periodic table – stretched out (7 rows) Shows periods with Lanthanide & Actinide

series where they really belong

The Periodic Law

Elements are also arranged into vertical columns

called Groups (or Families). Sounds of musical notes separated by an octave are related, but they are not identical. Properties of elements in a Group (column) are

related, but not identical. Groups - Each column is a Group (or Family).

Similar electron configurations Similar chemical properties

The Periodic Law

Example: Group 8A (or 18) - Noble Gasses with Full Shells

Helium - Atomic #2

Neon - Atomic #10

Argon - Atomic #18

The Periodic LawPeriodic Table of the Elements

Largest class of elements on the Periodic Table - Metals. 80% of the elements.

Metals

Malleable and ductile (can change

shape) Malleable = compress without breaking Ductile = stretch without breaking

Good Conductors (thermal & electrical) Luster (means they are shiny!)

Physical Properties of Metals

Groups 3 – 12: Form a bridge between elements on the left and right side of the table

Tough, hard, and strong Less reactive than standard metals Have more properties in common than elements in other groups.

Transition Metals

Share characteristics of both metals & non –

metals. Semi – conductors

Metalloids

Insulators (poor conductivity) Living organisms are mostly non-metals.

(especially C, N, O, H) Most of the compounds in your body contain

carbon

Non-Metals

Across a period from left to right, the elements

become less metallic and more nonmetallic in their properties.

From left to right across Period 3, there are three metals (Na, Mg, and Al), one metalloid (Si), and four nonmetals (P, S, Cl, and Ar).

Variations Across a Period

Sodium reacts violently with water. Magnesium will not react with water unless the

water is hot. Aluminum does not react with water, but it

does react with oxygen. Silicon is generally unreactive. Phosphorus and sulfur do not react with water,

but they do react with oxygen. Chlorine is highly reactive. Argon hardly reacts at all.

Variations Across a Period