C2
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How were the element arranged in the early period table
Arranged by atomic weight
Who proposed law of octaves
Newlands
What does law of octaves suggest
Properties of every eighth element were similar
What does the group number on the periodic table equal
Number of electrons on outer shell
Give the properties of alkalis metals
Reactive Soft Low density Low melting point
What do the melting and boiling points do as you go down group 1
Decrease
Why does the reactivity of the alkalis metals increase going down the group
the atoms get larger so the outer electron gets further from the nucleus, the electrostatic attraction decreases due to the shielding of inner shells
What group is the halogens part of
Group 7
What are the halogens
Non metals
What are the melting and boiling points like in the halogens
Low that increase going down the group
What do halogens easily form
Covalent compounds
Do the halogens conduct electricity
Poor conductors
What does the reactivity do going down the halogens
Decrease
Why does the reactivity decrease going down the halogens
The outer electron gets further away from the positive nucleus so the force needed to pull another electron in gets weaker
Why does the reactivity of metals increase going down the group
When metals react they lose electrons
Where r the transition elements found
between Groups 2 and 3
Give some properties of transition elements
Good conductors hard and strong High melting points Not reactive
What does chlorine look like
Green toxic gas
What does bromine look like
Red poisonous liquid
What does iodine look like
Poisonous purple vapours
What are transition metals used for
Industrial catalysts
What do compounds with alkalis metals usually do
Dissolve in water to form colourless solutions
how was the periodic table developed
first scientists arranged elements in atomic weight 1864 newlands proposed law of octaves but new elements did not fit this law 1869 mendeleev placed elements in atomic weight to find patterns he left gaps for undiscovered elements and so elements of the same group had similar properties