The Periodic Table Flashcards
What was the first idea about the periodic table?
1808, John Dalton arrnaged the elements by atomic weight. Only 20 elements were listed and not all were actually elements.
What was the second idea about the periodic table?
1864, John Newlands organised the elements into eights.
What was the third idea about the periodic table?
1869, Dmitri Mendeleev took the 50 known elements and arranged them into a table with various gaps. He put them mainly in order of atomic weight but did switch that order if the properties meant it should be changed. He predicted the properties of the undiscovered elements ans when these were discovered and were about the same it helped confirm his ideas.
What did the discoverey of isotopes do?
It confirmed that Mendeleev was correct to not place elements in a strict order of atomic weight but to take in their properties. Because isotopes of the same element have different masses but the same properties.
What is the modern periodic table like?
The elements are arranged by atomic number
What does the group number tell you?
The amount of electrons in the outer shell.
What does the periods tell you?
A new full shell of electrons
Why do elements in the same group react similarly?
Because they have the same number of electrons in their outer shells.
What are the properties of a metal?
Conduct electricity and heat
Ductile
Malleable
Strong
High boiling and melting points
What are the properties of non-metals?
Dull looking
Brittle
Don’t conduct electricity
Lower density
Aren’t always solid at room temperature
What are group 0 elements known as?
Noble gases
What are the properties of noble gases?
They all have 8 electrons in their outer shell (apart from helium which has 2)
They don’t react at all
They are monatomic gases (single atoms not bonded to each other)
They are colourless at room temperature
They aren’t flammable
What are the trends of the noble gases?
The boiling points increase as you move down.
What is group 1 known as?
Alkali metals
Properties of alkali metals?
Soft and low density
Trends of the alkali metals?
Increasing reactivity as you go down
Lower melting points and boiling points
Higher relative atomic mass
How do alkali metals react with water?
Lithium - fizzes, melts and moves on surface.
Sodium - Fizzes more, melts, moves on surface, may catch fire with a yello-orange flame.
Potassium - fizzes more, melts, moves on surface, may catch fire with lilac flame.
How do the alkali metals react with chlorine?
Lithium - Burns to give white solid
Sodium - Burns to give white solid
Potassium - Burns to give white solid
How do alkali metals react with oxygen?
Lithium - Burns with a red flame to give a white solid.
Sodium - Burns with a yellow-orange flame to give a white solid.
Potassium - Burns with purple flame to give a white solid.
What are the products of reacting alkali metals and non-metals?
They form ionic compounds that are white solids and dissolve in water to form colourless solutions.
What is group 7 called?
The halogens
What is each of the halogens?
Flourine - poisonous yellow gas
Chlorine - fairly reactive, poisonous dense green gas
Bromine - dense, poisonous red-brown volatile liquid
Iodine - dark grey crystalline solid or a purple vapour
What are the trends of the halogens?
Less reactive as you go down
Higher melting and boiling points
Higher relative atomic masses
What is a displacement reaction?
When a more reactive halogen displaces a less reactive halogen from solutions of its salts.
Explain reactivity trends within groups?
Larger atoms lose electrons more easily going down a group.
Larger atoms gain electrons less easily going down a group.
This is because the puter electrons are further away from the attractive force of the nucleus. The inner shells screen or shield the outer electrons from the positive charge of the nucleus.
Properties of transition metals?
conduct electricity and heat
Hard and strong
High density
High melting points (with the exception of mercury)
Much less reactive than alkali metals
They can have more than one ion
They are often coloured
There compounds make very good catalysts
