3a) Elements, Water And Organic Chemistry Flashcards
How did Newlands organise his elements?
They were arranged in octaves (8s)
Every 8th had similar properties
In the 1800s how could elements be classified?
By physical properties
Chemical properties
Relative atomic mass
Why did Newlands method not work?
Why did the scientific community not like it?
He didn’t leave gaps for undescovered elements
His groups had elements without similar properties
He mixed up metals and non metals
How was Dmitri Mendeleev’s periodic table organised?
In order of atomic mass
He left gaps for undescovered elements so could predict their properties
Elements with similar properties were put in groups (vertical columns)
Describe the modern periodic table.
Arranged by electronic structure - you can predict their chemical properties
Shells hold electrons
Groups have the same no. of electrons in their outer shell
The more shells the less attraction
Describe the changes as you go down group 1 (alkali metals)
Elements become more reactive (outer electron more easily lost - further from the nucleus)
Lower melting and boiling points
What type of compounds are made when group one and seven bond?
Why does this happen?
Ionic compounds
Lose their one outer shell electron to form a 1+ ion.
Produce white compound which dissolve in water to form colourless solutions
What happens as you go down group seven (halogens)?
Less reactive - harder to gain an electron - further from the nucleus
Higher melting and boiling points
Name the coloured vapours that halogens form
Fluorine: very reactive, yellow gas
Chlorine: fairly reactive, dense green gas
Bromine: red brown volatile liquid
Iodine: dark grey crystalline solid or purple vapour
Describe the properties of transition elements
Good conductors
Dense, strong, shiny
Less reactive don’t react as vigorously as group 1
Higher melting points
List the coloured compounds of transition metals
Potassium chromate VI: yellow
Potassium manganate VII: purple
Copper II sulphate: blue
List the use of transition metals as catalysts
Iron: haver process - ammonia
Manganese IV oxide: decomposition of hydrogen peroxide
Nickel: oils into fats - margarine
Describe the properties of hard water
Build up of scum - dissolved Ca ions and Mg ions react with soap
When heated creates scale (which reduced the efficiency off appliances)
Advantages of hard water
Ca2+ is good for bones and teeth
People who live with it are “less likely to develop heart disease”
How is temporary hardness removed?
By boiling. The Ca HCO3 decomposes to form CaCO3
