the Periodic table Flashcards
Dimitri Mendeleev
Carried out the most important work for the development of the modern periodic table
Differences between Mendeleev’s Periodic table and the modern Periodic table
Mendeleev’s periodic table
- elements arranged in order of increasing atomic mass
- Gaps left for undiscovered elements – fewer elements
- No noble gases present – not discovered
- No block of transition metals – included in groups
- The actinides and lanthanides not present
Modern day
- elements arranged in order of increasing atomic mass
- no gaps – more elements
- Block of transition elements present between groups two and three
- actinides and lanthanides are present (block of elements at bottom of periodic table)
Groups
Vertical columns
Periods
Horizontal columns
Alkali metals
- group one
- most reactive metals
Alkaline earth
- group two
- less reactive than group one
Transition metals
- quite un reactive metals
- form coloured compounds
Halogens
- group seven
- most reactive non-metals 
Noble gases
- group 0/8
- un reactive non-metals
Which metal isn’t a solid?
Mercury
What is the only liquid non-metal?
Bromine
Are there any solid non-metals
Several
How does the group number affect the number of electrons in the outer shell?
- as the group number increases so does the number of electrons in the outer shell
- the group number is equal to the number of electrons in the outer shell
What is the period number equal to?
The number of shells in use
Where are metals found on the periodic table?
On the left of the stepped line
Where are non-metals found on the periodic table?
On the right of the stepped line
What do metals burn in oxygen to form?
Solid basic oxides
What is an example of a metal burning in oxygen?
magnesium —-> grey solid burns with bright, white light and white ash is formed
What do non-metals burn in oxygen to form?
Gaseous acidic oxides
What is an example of a non-metal burning in oxygen?
Sulfur —-> yellow solid burns with a blue flame and a colourless, pungent gas is formed
How can metals and non-metals be distinguished?
According to their properties
- conduction of heat
- energy
- ductility
- malleability
- melting points
- sonority
What does group one contain?
The most reactive metals
What are the metals in group one called?
Alkali metals
What is the valency of group one elements?
One
How many electrons do group one elements have in their outer shells?
One
What happens when group one elements react?
- they lose one electron
- form positive ions
- form ionic bonds
What are the textures of alkali metals?
- soft
- shiny when freshly cut
- tarnish rapidly in oxygen
What density do alkali metals have?
Low density
Which alkali metals are less dense than water?
- Lithium
- Sodium
- Potassium
Why are alkali metals stored in water?
So they do not react with moisture and oxygen in the air
How is reactivity measured in group one?
It increases going down group one
observations for Lithium reacting with water
- metal floats
- moves around the surface of the water
- bubbles of gas
- heat is released
- metal disappears
- colourless solution forms
- turns universal indicator purple/blue —-> strong alkali
Equation for Lithium reacting with water
2Li + 2H2O —-> 2LiOH + H2
Observations for Sodium reacting with water
- vigorous reaction
- moves around surface of water
- sodium melts, forms a silver ball
- bubbles of gas
- heat is released
- metal disappears
- colourless solution forms
Equation of Sodium reacting with water
2Na + 2H2O —-> 2NaOH + H2
Observations for Potassium reacting with water
- vigorous reaction
- metal floats around surface of water
- burns with lilac flame
- bubbles of gas
- heat is released
- metal disappears
- colourless solution is formed
Equation for Potassium reacting with water
2K + 2H2O —-> 2KOH + H2
General equation for metal reacting with water
Metal + water —-> metal hydroxide + hydrogen
Why does reactivity increase going down group one?
Atoms get bigger due to there being more shells of electrons
Outer shell electron is further away from positive charge of nucleus
Outer negative electron will be less strongly attracted to positive nucleus- easier to lose
Easier electron is to lose more reactive the alkali metal
What are safety measures taken durning experiments?
safety screen
- prevents corrosive hydrogen solution from splashing out or metal sparking out and causing damage to skin
Safety goggles
- prevents corrosive hydrogen solution from splashing into eyes and causing damage
How many electrons do the halogens have in their outer shells?
Seven
What is the valency of the halogens?
One
What do they exist as on their own?
Diatomic molecules
Halide ion
Halogen gains one electron from metal atom
Physical properties of halogens
Increased van der Waals’ forces between molecules leads to increased melting points and decreased toxicity
What happens when Iodine is heated?
- grey- black solid changes to a purple vapour on heating
- purple vapour changes back to grey-black crystals on cooling
Sublimation
Change of state from a solid directly to a gas on heating without passing through liquid state
Observations of Chlorine reacting with Sodium Bromine solution
Colourless solution turns orange
Observations for Chlorine reacting with Sodium Iodide solution
Colourless solution turns brown
Observations for Bromine reacting with sodium iodide solution
Colourless solution turns brown
Equations for chlorine + sodium bromide
Chlorine + sodium bromide —-> sodium chloride + bromide
Symbol equation
Cl2 + 2NaBr —-> 2NaCl + Br2
Ionic equation
Cl2 + 2Br- —-> 2Cl- + Br2
Test for Chlorine
damp universal indicator paper turns red and then bleaches white
Equations for Bromine + Sodium Iodide
Bromine + sodium iodide —-> sodium bromide + iodine
Symbol equation
Br2 + 2NaI —-> 2NaBr + I
Ionic equation
Br2- + 2I- —-> 2Br- + I2
How is reactivity shown in group seven?
Reactivity decreases going down group seven
What will happen when halogens react in an aqueous solution of salt
A more reactive halogen will displace a less reactive halogen from an aqueous solution of its salt
characteristics of a group seven ion
- stable
- single negative charge
Half equations for group seven atoms
Cl + e- —-> Cl-
Br + e- —-> Br-
I + e- —-> I-
Half equations for group seven molecules
Cl2 + 2e- —-> 2Cl-
Br2 + 2e- —-> 2Br-
I2 + 2e- —-> 2I-
What do you do when a half equation for a halide ion is asked for?
Check whether it is from an atom or molecule
Why is it more difficult to attract an electron down group seven
- down the group atoms have more shells of electrons
- outermost she’ll is further away from the nucleus
- force of attraction between positive nucleus and electron decreases
physical properties of group one metals
Low, melting point
Low density
- Li, Na, and K less dense than water - float
very reactive with water
- form metal hydroxide + hydrogen
Physical properties of transition metals
High melting point
– except Mercury
high density
Low reactivity with water
– some metals react with steam e.g Fe, to form metal oxide + hydrogen
Characteristics of noble gases
Stable
– do not react as they have a full outer shell of electrons
exist as single atoms
colourless gases
Boiling points increase down the group - Van der Waals forces increase in strength down the group
