### The Modern Periodic Table

```Chapter 5.2
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

 Most often there are 4 pieces of information for each
element listed on the periodic table.
Atomic number
(# of protons)
Element Information in the
Periodic Table

 Most often there are 4 pieces of information for each
element listed on the periodic table.
Atomic number
Element symbol
(1st capital, 2nd small)
Element Information in the
Periodic Table

 Most often there are 4 pieces of information for each
element listed on the periodic table.
Atomic number
Element symbol
Element name
Element Information in the
Periodic Table

 Most often there are 4 pieces of information for each
element listed on the periodic table.
Atomic number
Element symbol
Element name
Atomic mass
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.

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.
The Periodic Law

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
All of the Electron Shells


The Periodic Law

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

Example: Group 8A (or 18) - Noble
Gasses with Full Shells

Helium - Atomic #2
Neon - Atomic #10
Argon - Atomic #18
The Periodic Law

Periodic Table of the Elements
Metals

 Largest class of elements on the Periodic Table - Metals.
 80% of the elements.
Physical Properties of Metals

Malleable and ductile (can change shape)
 Malleable = compress without breaking
 Ductile = stretch without breaking
Good Conductors (thermal & electrical)
Luster (means they are shiny!)
Transition 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.
Metalloids

 Share characteristics of both metals & non – metals.
 Semi – conductors
Non-Metals

 Insulators (poor conductivity)
 Living organisms are mostly non-metals. (especially
C, N, O, H)
 Most of the compounds in your body contain carbon
Variations Across a Period

 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.
```