1.1 Periodic Table
The Greek Philosophers were the first people to propose that all matter was composed of tiny particles
They proposed all matter was composed of tiny indivisible pieces
an Element is a substance that cannot be split up into simpler substances by chemical means
Humphrey David discovered the elements potassium, sodium, barium, strontium and magnesium
Johann Dobreiner arranged elements in groups called triads. A triad is a group of 3 Elements with similar chemical properties in which the atomic weight of the middle element is approximately equal to the average of the other two.
John Newland arranged elements in order of increasing atomic weight in groups called octaves. The first and eighth elements had similar properties. They didn’t always work as many elements weren’t discovered at the time.
Newlands Octaves are groups of elements arranged in order of increasing atomic weight in which the first and the eighth element of each group had similar properties.
Dmitri Mendeleev
Mendeleev arranged elements in order of increasing atomic weight
Mendeleev’s Periodic Law; When elements are ordered by increasing atomic weight ( Relative atomic Mass) the properties of the elements vary periodically
He placed elements with similar properties in vertical columns called groups.
He left gaps in his table to make elements fit into the proper columns. These gaps were for undiscovered Elements
In a few cases, he had to reverse the order of elements to make them fall into groups of elements with similar properties. (i.e Te + I )
Henry Mosely used XRays to determine the atomic number of elements. By arranging the elements in order of increasing atomic number there was no need to reverse the order as Mendeleev did.
The modern periodic table is an arrangement of all known elements in order of increasing atomic numbers
Determining the atomic number of an element
Determining the mass number of an element
Determining the chemical symbol of an element
Grouping together the elements with similar physical and chemical properties
Try to demonstrate trends in the physical and chemical properties of elements
Distinguishing between metals and non-metals
Relative Atomic Mass is defined as
The average of the mass numbers of the isotopes of the element
As they occur naturally
Taking their abundance into account
Expressed on a scale in which the atoms of the carbon 12 isotope will have a mass of exactly 12 units
Group 1 Alkali Metals
H, Li, Na, K,Rb , Cs ,Fr
Stored under oil to prevent them from reacting with oxygen and water
Soft Shiny Highly reactive metals
Reactivity increases down the group
One electron on the outer shell
They react with oxygen to form oxides
They react with water to form hydroxides
Group 2 Alkaline Earth Metals
Be, Mg, Ca, Sr, Ba, Ra
Harder metals than Alkali metals
Reactivity increases down the group
2 electrons on the outer shell
Readily form divalent cathons
Group 7 The Halogens
F, Cl, B, I, At
Fluorine + Chlorine are gases, Bromine is a liquid, and Iodine and Astatine are gases
7 electrons on the outer shell
Very reactive
Reactivity decreases down the group
Oxidising agents
Group 8 Noble Gases
He, Ne, Ar, Kr, Xe, Rn
Very unreactive
Full outer shell
Do not form compounds
Boiling points increase down the group
#Wrote this chapter with Azazel my leopard gecko. if you are not me and you reading this Azazel solos your pet
The Greek Philosophers were the first people to propose that all matter was composed of tiny particles
They proposed all matter was composed of tiny indivisible pieces
an Element is a substance that cannot be split up into simpler substances by chemical means
Humphrey David discovered the elements potassium, sodium, barium, strontium and magnesium
Johann Dobreiner arranged elements in groups called triads. A triad is a group of 3 Elements with similar chemical properties in which the atomic weight of the middle element is approximately equal to the average of the other two.
John Newland arranged elements in order of increasing atomic weight in groups called octaves. The first and eighth elements had similar properties. They didn’t always work as many elements weren’t discovered at the time.
Newlands Octaves are groups of elements arranged in order of increasing atomic weight in which the first and the eighth element of each group had similar properties.
Dmitri Mendeleev
Mendeleev arranged elements in order of increasing atomic weight
Mendeleev’s Periodic Law; When elements are ordered by increasing atomic weight ( Relative atomic Mass) the properties of the elements vary periodically
He placed elements with similar properties in vertical columns called groups.
He left gaps in his table to make elements fit into the proper columns. These gaps were for undiscovered Elements
In a few cases, he had to reverse the order of elements to make them fall into groups of elements with similar properties. (i.e Te + I )
Henry Mosely used XRays to determine the atomic number of elements. By arranging the elements in order of increasing atomic number there was no need to reverse the order as Mendeleev did.
The modern periodic table is an arrangement of all known elements in order of increasing atomic numbers
Determining the atomic number of an element
Determining the mass number of an element
Determining the chemical symbol of an element
Grouping together the elements with similar physical and chemical properties
Try to demonstrate trends in the physical and chemical properties of elements
Distinguishing between metals and non-metals
Relative Atomic Mass is defined as
The average of the mass numbers of the isotopes of the element
As they occur naturally
Taking their abundance into account
Expressed on a scale in which the atoms of the carbon 12 isotope will have a mass of exactly 12 units
Group 1 Alkali Metals
H, Li, Na, K,Rb , Cs ,Fr
Stored under oil to prevent them from reacting with oxygen and water
Soft Shiny Highly reactive metals
Reactivity increases down the group
One electron on the outer shell
They react with oxygen to form oxides
They react with water to form hydroxides
Group 2 Alkaline Earth Metals
Be, Mg, Ca, Sr, Ba, Ra
Harder metals than Alkali metals
Reactivity increases down the group
2 electrons on the outer shell
Readily form divalent cathons
Group 7 The Halogens
F, Cl, B, I, At
Fluorine + Chlorine are gases, Bromine is a liquid, and Iodine and Astatine are gases
7 electrons on the outer shell
Very reactive
Reactivity decreases down the group
Oxidising agents
Group 8 Noble Gases
He, Ne, Ar, Kr, Xe, Rn
Very unreactive
Full outer shell
Do not form compounds
Boiling points increase down the group
#Wrote this chapter with Azazel my leopard gecko. if you are not me and you reading this Azazel solos your pet