The periodic table of elements

Elements
Science has come along way since Aristotle’s theory of Air, Water, Fire, and Earth.
Scientists have identified 92 Natural elements, and created about 28 others.

Elements
The elements, alone or in combinations, make up our bodies, our world, our sun, and in fact, the entire universe.

Periodic Table
A great deal of information about an element can be gathered from its position on the period table.
Understanding the organization and plan of the periodic table will help you obtain basic information about each of the 118 known elements.

Periodic Table

Metals

Properties of Metals
Metals appear to the left of the dark ziz-zag line on the periodic table. Most metals are solid at room temperature.

Properties of Metals
Metals have luster. This means they are shiny

Properties of Metals
Ductile
metals can be drawn into wire.

Properties of Metals
Malleable
metals can be hammered into sheets

Properties of Metals
Metals have a high melting point. They are also very dense.

Properties of Metals
Conductors
Metals are good conductors of electricity and heat

Properties of Metals
A chemical property of metal is its reaction with water and oxygen. This results in corrosion and rust.

Metals
Uses, Properties and Structures and Modifying Metals

Metals can be seen all around us
We use metals because they have many useful properties
Can you name some properties of metals that make them useful for
Electrical wires
Frames for houses
Taps

Metals (notes)
Most elements are metals. 88 elements to the left of the stairstep line are metals or metal like elements.
Physical Properties of Metals:
Metals have Lustre (shininess)
Good conductors of heat and
electricity
High density (heavy for their size)
High melting point
Ductile (most metals can be drawn
out into thin wires)
Malleable (most metals can be hammered into thin sheets)
Chemical Properties of Metals:
Easily lose electrons
Corrode easily. Corrosion is a gradual wearing away. (Example: silver tarnishing and iron rusting)

Exceptions to the rule
Mercury is liquid at room temperature
Alkali metals (group 1) can be cut with a knife at room temperature
Looking at Table 5.1 pg 79 where would you draw the line between metals and non metals

How would you test for hardness?
Electrical conductivity?
Heat conductivity?

Properties and Structures of Metals

Metallic bonding model
In a solid sample of a metal:
1. Positive ions are arranged in a closely packed structure. This is called a regular three dimensional lattice of positive ions.
The ions occupy fixed positions in a lattice

Metallic Bonding Model
2. The Outermost electrons (valence electrons) of metals wander freely through metallic lattice. These are called delocalised electrons.
Metal consists of cations
held together by negatively-
charged electron "glue.“
delocalised electrons are not associated with a single atom
or to a bond.

3. The ions in the lattice are held together by electrostatic forces and delocalised electrons
Electrostatic forces are the forces between particles that are caused by their electric charges
This attraction extends throughout the lattice and is called metallic bonding.
Metallic Bonding Model

Limitations to Metallic bonding model
Some properties of metals cannot be explained by the metallic bonding
1.The range of melting points, densities
2. Magnetic nature of cobalt iron and nickel
3. Differences in electrical conductivity
4. Solubility in water and corrosion

Metal crystals model
Some of these limitations can be explained by the metal crystal model
Metals form crystals, large or small
Cations
Delocalised electrons between Cations
Large metal crystals
small metal crystals

Piece of metal ?metal crystals? lattice of ions and electrons
The Metallic bonding model refers the arrangement of particles (electrons etc) in one metal crystal.
A piece of a metal
consists of a large
number of crystals.
Where one crystal meets
another the regular lattice
is disrupted

Explaining properties of metals
Why do metals have relatively high boiling points?
The strong attraction (electrostatic forces) between the positive cations and delocalised electrons holds the metallic lattice together making it hard to loosen the bonds.

Why are metals good conductors of electricity and heat?
Delocalised (free) electrons can move rapidly in response to electric fields and transmit heat, hence metals are a good conductors of electricity and heat.

Why are metals malleable and ductile?
The layers of atoms in metal are hard to pull apart because of the electrons holding them together, hence metals are tough.
Individual atoms are not held to any other specific atoms, hence atoms slip easily past one another. Thus metals are ductile and malleable.

Why are metals hard?
Strong electrostatic forces between the cations and electrons make it difficult to separate particles from one another
Why are metals lustrous(shiny)?
When light energy hits the delocalised electrons they absorb the energy and jump and energy level, when they go back down a level they release energy in the form of a photon hence the shininess

Modifying metals
Alloys, heat treatment and work hardening

Modifying Metals
Few metals are used in their pure form
Most metals need to be changed in some way so they can be used. This
may include treating the
metals and combining metals
Example: Iron is not hard enough by itself to be used so we use steel.
Steel is made by mixing
iron with about 2% carbon

A: Alloys
Properties of metals can be significantly altered by adding other substances, usually a metal or carbon.
The substances are melted together and mixed then allowed to cool. This is called an alloy.
Note no chemical reaction has taken place it is just a mixing of two metals
There are two types of alloys malleable and ductile
Substitutional alloys
interstatial

White gold is an alloy of gold and at least one white metal, usually nickel or palladium
Rose gold is a gold and copper alloy widely used in jewellery due to its reddish colour.
Electrical transmission wires are made from an aluminium alloy

1. Substitutional alloys
Substitutional alloys are made from elements that have similar chemical properties
Example: Copper and Gold make rose gold
+
?

2. Interstitial alloys
In interstitial alloys a small proportion of a smaller atoms is added to a metal
Example: Carbon and iron make steel
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B: Hardening Metals
The way a metal is prepared can have a large impact on how it behaves
Many metals are prepared in the liquid state and cooled. The rate at which it cools can have a significant effect on the properties of the solid