The Periodic Table and it's characteristics
The periodic table is a way of classifying the elements.
Metals and non-metals are separate by a line, non-metals are in the right (except from hydrogen)
The rows are called periods, elements are classified in them arrange in numbers form 0 to 7.
Periods
The period number tells you the number of electron shells in the atoms.
Elements
They show periodicity
Elements with similar properties appear at regular intervals.
Similar elements are arranged in columns
Metals and non-metals
Metals are to the left of the zig-zag line. There are more metals than non-metals
80% of the elements are metals. They have different properties
Hydrogen
Hydrogen sits alone
it has one outer electron
Transition elements
In the block of the middle of the period table, are all metals.
Artificial elements
some of the elements in the table are artificial, they have been created in lab
These artificial elements are radioactive, and their atoms break down very quickly.
Patterns and trends in the periodic table
Elements in a group behave in a similar way, but they also show trends.
Across a period there is another trend: a change from metal to non-metal. So if you know where an element is, in the Periodic Table, you can use the patterns and trends to predict how it will behave
When arranged by proton number, the elements show periodicity.
Groups
The same as the number of outer-shell electrons in the atoms.
All elements in groups have similar reactions .
The outer shell electrons are also also called valency electrons
There are groups with special names and different functions.
Group I: The alkali metals
Group VII: the halogens
Group 0: the noble gases
The transition elements
They are in group 1 of the periodic table, only some of the elements are safe to keep in the school lab. The rest are violently reactive
Alkali metals are NOT typical metals.
Groups
They are softer than other metals. (You can cut them with a knife).
They have low density, which makes them lighter.
They float on water.
Comparing them with most metals, they have low melting and boiling points.
Atoms in this group have a very stable arrangement of electrons in their outer shells. This make them UNREACTIVE.
All the elements in a group have similar reactions, because they have the same number of valency electrons.
Like any family, alkali metals are all a little different. There is an overall increase or decrease for each property, as you go down the table, they have patterns called trends.
They have 3 different types of reactions
Reaction with water
Reaction with chlorine
Reaction with oxygen
They react vigorously with water. Hydrogen bubbles off living solutions. Which are alkalis
If you heat three metals, and plunge them into gas jars of chlorine, they burst into flame.
Three metals also burst into flame when you heat them and plunge them into gas jars of oxygen.
They three react in a similar way because they have the same number of valency
They are so reactive because they need to loose only one electron, to gain a stable outer shell. They become ions, so the compounds they form are ionic.
This is a non-metal group. The elements that contain are usually called halogens.
The trends in their chemical properties
Halogens are among the most reactive elements in the periodic table. They react with metals to form compounds called halides.
They all react in a similar way
They halogens react in a similar way because their atoms all have 7 valency electrons.
They are very reactive because their atoms need just one more electron to reach a stable outer shell of 8 electrons. So they have a strong drive to react with other elements or compounds, to gain.
When the atoms react with metal atoms they accept electrons, forming halide ions.
With non-metal atoms such as hydrogen and carbon, they share electrons, forming molecules with covalent bonds.
How they react with halides
When chlorine water (a solution of chlorine) is added to a colourless solution of potassium bromide, the solution turns orange.
And when chlorine water is added to a colourless solution of potassium iodide, the solution turns red brown.
This group is of non-metals, colourless gases, which occur naturally in air. Also these elements are monatomic (they exist as single atoms).
They are unreactive, this is their most striking property. They don't normally react with anything. That is why they are called noble.
This atoms, in difference of others already have a stable outer shell with 8 electrons.
Uses of noble gases
They are unreactive or inert, which makes them safe to use.
They also glow when a current is passed through them at low pressure. These properties lead to many uses.
Helium is used to fill balloons and air ships, because its much lighter than air.
Argon is used to provide an inert atmosphere. For example is used as a filter in tungsten light bulbs.
Neon is used in advertising signs. It glows red, but the color can be changed by mixing it with other gases.
Krypton is used in lasers, for example for eye surgery and in car headlamps.
Xenon gives a light like bright daylight, but with a blue tinge. It is used in lighthouse lamps, lights for hospital, operating rooms, etc.
They are the block of 30 elements in the middle of the Periodic table. They are all metals, and include most of the metals we use every day.
Their physical properties
Iron
Copper
Nickel
the most widely used metal: grey with a metallic lustre.
Reddish with a metallic lustre
Silvery with a metallic lustre
The transition elements share these physical properties:
Hard, tough and strong
High, melting points
Malleable
good conductors of heat and electricity
High density
In the elements of period 2, atoms have two electron shells.
In period 3 they have three, and so on.
This is because it has one outer electron, and forms a positive ion.
Bibliography
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