CHAPTER 2 THE PERIODIC TABLE Flashcards
Timeline of development of periodic table (1808,1864,1869)
John dalton(1808) - 20 elements arranged in increasing weight order. The symbols were random with not all being elements.
John newlands(1864) - 62 elements arranged into 8s(octaves) grouped by similar reactions. However not all element were found so table broke down and didn’t work after first elements 20.
Dmitri Mendeleev(1869) - 63 elements arranged in order of increasing atomic weight and grouped by chemical similarity. He left gaps for when new element were discovered - they fitted perfectly.
What number determines an elements place in the periodic table
Atomic (proton) number
What determined an elements chemical properties
The number of electrons in the outermost shell
What does the group number equal
The number of electrons in the outermost shell
Why are noble gases un reactive
Stable electron arrangements - 0 in outershell
What is group 1 called
Alkali metals
Do melting/boiling points increase/decrease as you go down the group
Decrease
What do all group 1 metals react with and what do they produce
Water to produce hydrogen and an alkaline solution containing the metal hydroxide.
Does the reactivity in group 1 decrease or increase as yougo down
Increase
What ions do group 1 metals form and what are they
1+ ions, generally white and dissolve in water giving colourless solutions
Why are alkali metals stored under oil
Stop them reacting with oxygen in the air
What is group 7 called
The halogens
What colour are the halogens and what state are they at room temp
Fluorine - pale yellow gas
Chlorine - pale green gas
Bromine - red/brown liquid
Iodine - grey/purple solid
Astatine - black solid
What ions do halogens form
Single negative charge in ionic compounds with metals
How do halogens form covalent compounds
By sharing electrons with other non metals
Does the reactivity increase or decrease as you go down the halogens
Decrease
Does the melting/boiling pikts increase or decrease as you go down the halogens
Increase
3 factors that affect the reactivity
Size of the atom
Shielding effect of inner electrons
Nuclear charge
