Chapter 3 - Periodic Table Flashcards
How and when developed the first periodic table ?
Dmitri Mendeleev in 1896
What were the features of Mendeleev’s periodic table ?
- left gaps for undiscovered elements
- listed the elements in increasing atomic weight
How do todays periodic table differ from Mendeleev’s ?
- Mendeleev’s had no noble gases
- gaps were left in his
- no block of transition metals in Mendeleev’s
- actinides and lanthanides not present in Mendeleev’s
What does the staircase line on the periodic table separate ?
The metals and the non-metals
What two elements are liquids and describe their appearance .
Bromine: red-brown liquid
Mercury: silvery-white liquid
What is a group ?
A group is a vertical column in the periodic table
What do all elements in the same group have in common ?
- similar chemical properties
- same number of electrons in their outer shell
What is the name of group 1 ?
alkali metals , reactive
What is the name of group 2 ?
alkaline earth metals , reactive
What is the name of group 7 ?
Halogens, reactive
What is the name of group 8 ?
noble gases, unreactive
What is a period ?
A period is a horizontal row in the periodic table
What are the physical properties of group 1 metals ?
- soft
- shiny
- low density
- grey solids
- low melting points
What is the equation shown when a group 1 metal reacts with water ?
Group 1 metal + water —-> metal hydroxide + hydrogen
What are the risk assessments when using group 1 metals ?
- use tweezers
- use a safety screen
- wear safety glasses
- use small pieces of metal
What are the observations when lithium reacts with water ?
- moves on surface
- bubbles
- heat released
- disappears
What are the observations when sodium reacts with water ?
- moves on surface
- bubbles
- heat released
- disappears
What are the observations when potassium reacts with water ?
- lilac flame
- moves on surface
- bubbles
- heat released
- disappears quickly
- crackles at end
What is the general half equation for a group one metal reaction ?
Group 1 metal atom —-> Group 1 metal ion + electron
Why does the reactivity of group 1 metals increase as you go down the group ?
The atom they need to lose becomes further away from the nucleus and is therefore easier to lose.
What are the physical properties of the halogens ?
Fluorine : yellow gas Chlorine: yellow-green gas Bromine: red-brown liquid Iodine: grey-black solid Astatine : - -
What is the trend of the halogens as they go down the group ?
- elements become darker
- change from a gas to liquid to solid
- increase in melting point
Explain toxicity regarding the halogens.
All the halogens are toxic, although toxicity decreases down the group.
What is sublimation ?
sublimation is the change of state from solid directly to gas on heating.
What happens if you heat iodine ?
it undergoes sublimation
What is the general half equation for group 7 atoms ?
halogen atom + 1 electron —> halide ion
What is the general half equation for a group 7 molecule ?
halogen molecule + 2 electrons – > 2 halide ions
What is the trend of reactivity of group 7 ?
As the group descends the reactivity decreases
Explain displacement reactions.
In a displacement reaction the more reactive halogen is added to the halide solution.
Give an example word equation for a displacement reaction
chlorine+potassium iodide -> iodine + potassium chloride
What is the appearance for a chlorine solution ?
pale green solution
What is the appearance for a bromine solution ?
orange solution
What is the appearance for a iodine solution ?
brown solution
What are the colour changes observed when chlorine reacts with a) bromine solution b) iodine solution
a) colourless solution changes to orange
b) colourless solution changes to brown
What are the colour changes observed when bromine reacts with iodine solution
colourless solution changes to brown
no reaction occurs between bromine and chlorine solutions
What are the colour changes observed when iodine reacts with chlorine, bromine and iodine solutions ?
no reaction occurs with any of them
What is the test for chlorine ?
Damp universal indicator paper changes to red and then bleaches white in the presence of chlorine gas
Why are Group 0 elements stable ?
They have a full outer shell of electrons
Give two physical properties of the noble gases.
- Low boiling point
- colourless
What happens to the boiling point as you go down Group 0 ?
The boiling point increases, because of the strength of the van der Waal forces holding them together.
What are the physical properties of transition metals ?
- high melting points
- high density
- low reactivity with water
- react to form ions with different charges
- form coloured compounds
What does copper(ii) oxide look like ?
black solid
What does copper(ii) carbonate look like ?
green solid
What does hydrated copper(ii) sulfate look like ?
blue crystals
What does copper(ii) salt in solution look like ?
blue solution
What are the three steps for writing a risk assessment ?
1: a list of all the hazards in the experiment
2: a list of all the risks a hazard could cause
3: suitable control measures you could take to prevent the risk
