Elements, Water And Organic Chemistry Flashcards
What used to be the two ways to categorise elements?
Their physical and chemical properties or their relative atomic mass.
What is the Newlands Law of Octaves?
He noticed that every eighth element had similar properties and so he listed some of the known elements in rows of sevens.
How many rows of seven were there for Newlands Law of Octaves?
Eight.
Which row did Newlands Law of Octaves break down on?
Third row with transition metals like titanium and iron.
Why was Newlands work criticised?
Contained elements that didn’t have similar properties eg carbon and titanium.
He mixed up metals and non metals eg oxygen and iron.
He didn’t leave any gaps for elements that hadn’t been discovered yet.
How did Dmitri Mendeleev put the elements in order?
Atomic mass but he found he had to leave gaps in order to keep elements with similar properties in the same vertical columns (groups).
Why was Dmitri Mendeleev leaving gaps really clever?
Predicted the properties of so far undiscovered elements.
What is the modern periodic table based on?
Electronic structure.
What can you predict using electron arrangement of elements?
The element’s chemical properties.
What are electrons in an atom set out in?
Shells which correspond to an energy level.
What do elements in the same group have?
The same number of electrons in their highest occupied energy level (outer shell).
What is the group number of an element equal to?
The number of electrons in the highest occupied energy level.
What charge attracts electrons and holds them in place?
Positive charge from the nucleus.
What happens to the attraction when the nucleus is further away from the electrons?
It decreases as the electron is shielded by more electron shells.
Why do Group 1 metals get more reactive as you go down the group?
The atoms of each element get larger so the outer shell electron gets further away from the nucleus and is shielded by more electron shells. The further an electron is from the positive nucleus, the easier it can be lost in reactions.
What effect does increased distance and shielding have on the reactivity of an element?
It is less likely to gain an electron as there is less attraction from the nucleus pulling electrons into the atom.
What happens as you go down Group 1?
They become more reactive, have lower melting and boiling points.
Do the alkali metals have low or high density?
Low.
Name the alkali metals.
Lithium, Sodium, Potassium, Rubidium and Caesium.
How many outer electrons does Group 1 have?
1 which makes them very reactive and gives them all similar properties.
What compounds do alkali metals form with non metals?
Ionic, they lose their outer electron to become 1+ ion. They hate the electron so won’t share (no covalent bonding).
What else do alkali metals make with non metals?
White compounds that dissolve in water to form colourless solutions.
What gas do alkali metals make with water?
Hydrogen gas.
Which alkali metals react vigorously with water?
Lithium, sodium or potassium.
What happens when you put lithium, sodium or potassium in water?
They float and move about the surface, fizzing furiously.
Which alkali metal is ignited in water?
Potassium.
How can you indicate hydrogen?
A lighted splint which will make a squeaky pop as the H2 ignites.