C3.1 The Periodic Table Flashcards
How were elements arranged and why?
In relative atomic mass, because scientists were not aware of atomic structure, so there was no such thing as atomic number
How did Newlands arrange his periodic table?
In order of atomic mass
What was Newlands’ Law of Octaves?
Every eighth element in his periodic table had similar properties
How did Newlands’ record his Octaves?
In rows of 7, elements with similar properties were in columns known as groups
Why was Newlands’ Periodic table criticised?
Some of the elements which had similar properties, didn’t, e.g. carbon and titanium
Metals and Non-Metals were in the same group
New elements discovered, didn’t fit his table
What did Mendeleev do that was different from Newlands?
He left gaps for undiscovered elements - these gaps predicted the properties of the elements
What did Mendeleev do that was similar to Newlands’ work?
Ordered in order of atomic mass and elements with similar properties were in columns (groups)
How is the modern periodic table arranged?
In order of atomic number
Why is the periodic table useful?
Helped to predict properties of undiscovered elements, useful summary of the structure of atoms
What do elements in the same group (column) have?
Apart from the transition metals, elements in the same group have the same number of electrons in their outer shells
What do elements in the same period (row) have?
Elements in the same group have the same amount of electron shells
What is shielding?
When inner electron shells reduce the attraction between the protons in the nucleus and outer electrons
How does shielding affect reactions?
More electron shells means it is easier to lose electrons and harder to gain electrons
How does the reactivity change in group 1 and why?
It increases as you go down the group - Group 1 metals react by losing an electron, so the more electron shells, the easier it is to lose an electron
How does the reactivity change in group 7 and why?
It decreases as you go down the group - Group 7 metals react by gaining an electron, so the more electron shells, the harder it is to gain an electron
What are the properties of the alkali metals (group 1 metals)?
Silvery solids that burn the skin, have a low density and have one electron in their outer shells
How does the melting and boiling points change as you go down group 1?
As you go down the group, the melting and boiling points decrease
How do the alkali metals react with non-metals?
They react to form ionic compounds
What are the compounds like when alkali metals react with non-metals?
White solids that dissolve in water to form colourless solutions
What is the word equation for the alkali metals with water?
Alkali metal + water ==> metal hydroxide + hydrogen
What is the reaction of water and the group 1 metals like?
Lithium, sodium and potassium float and move around the surface of the water fizzing furiously
What happens when you react the elements below potassium with water?
They react explosively
What happens to the solution when the alkali metals react with water?
The hydroxides produced dissolve in the water to give an alkaline solution
What is the test for Hydrogen?
The Squeaky Pop test - A lit splint is placed near where the reactants are reacting, if hydrogen is present a squeaky pop will be heard
What is the coloured vapour of Fluorine?
A poisonous yellow gas
What is the coloured vapour of Chlorine?
A poisonous dense green gas
What is the coloured vapour of Bromine?
A dense, poisonous, red-brown volatile liquid
What is the coloured vapour of Iodine?
A dark grey crystalline solid or a purple vapour
How do the Halogen (group 7) elements presented?
They exist as molecules which are pairs of atoms
How does the melting point and boiling point change as you go down Group 7?
As you go down the group, the melting and boiling points of the elements increase
How do the Halogens react?
They need to gain an electron forming 1- ions known as the halide ions
What happens when the Halogens react with metals?
They gain an electron forming ionic compounds
What happens if a more reactive halogen is added to a solution containing a less reactive halogen?
The more reactive halogen displaces the less reactive halogen
What are the properties of the transition metals?
They’re: Good conductors of heat and electricity, and are very dense, strong and shiny
What’s different between the transition metals and the alkali metals?
The T’ metals are less reactive than the A’ metals,
T’ metals are much denser, stronger and harder,
T’ metals have higher melting points than the A’ metals
Name some transition metals which can form ions with different charges
Iron (Fe): Fe2+ or Fe3+ ions
Copper (Cu): Cu+ or Cu2+ ions
Chromium (Cr): Cr2+ or Cr3+ ions
What colour are compounds containing Fe2+?
Green
What colour are compounds containing Fe3+?
Yellow
Where are transition metal compounds found?
The colours in gemstones; like blue sapphires and green emeralds, and the colours in pottery glazes are due to transition metals
What can the transition metals be used as?
Catalysts, e.g. Iron in the Haber process
