🧪 | Unit 9 | Periodic Table Flashcards
What are Group 7 elements called?
Halogens
Name the halogens?
Flourine, Chlorine, Bromine, Iodine, Astatine
Characteristics of halogens
- non-metals
- poisonous in elemental form
- have 7 valence electrons
- form anions with -1 charge
- m.p., b.p. and density increases down the group
- reactivity decreases down the group
At room temperature, what state of matter is F?
Gas
At room temperature, what state of matter is Cl?
Gas
At room temperature, what state of matter is Br?
Liquid
At room temperature, what state of matter is I?
Solid
At room temperature, what state of matter is At?
Solid
Colour of F?
Yellow
Colour of Cl?
Pale-green
Colour of Br?
Reddish-brown
Colour of I?
Grey solid, sublimes into a purple vapour
Colour of At?
Black, radioactive solid
What is the trend in the reactivity of halogens as you go down the group?
The reactivity decreases as you go down the group.
What colour are alkali metals when they are freshly cut?
Shiny, silvery surfaces when they are freshly cut.
What is the density of alkali metals?
They have low densities
What is the m.p. of alkali metals?
They have low m.p.
Which Group is diatomic?
Group VII
What is a halogen displacement reaction?
It’s when a more reactive halogen displaces a less reactive halogen in an aqueous solution of its halide.
What are Group 1 elements called?
Alkali metals
Characteristics of alkali metals
- soft metals
- have shiny, silvery surfaces when freshly cut
- form alkaline solutions with high pH values when reacting with water
- low m.p. and low density
- density increases as you go down the group
- m.p. decreases as you go down the group
- conduct heat and electricity
What is the trend in the reactivity of alkali metals as you go down the group?
The reactivity increases as you go down the group.
Observations: Li reacting with water
- fizzing (bubbles of H₂ produced)
- floats and moves around on the surface of the water
- dissolves into the water to produce an alkaline solution
Observations: Na reacting with water
- bubbles of H₂
- melts into a shiny ball that dashes around the surface
- floats on water
- orange flame
- white trail of sodium hydroxide produced, dissolves in water and forms alkaline solution
Why does Na/K melt when reacting with water?
Because alkali metals have low melting points and the reaction generates a lot of heat.
How can the Na/K float on water, when reacting with water?
Because it is less dense than water
How does the shiny ball of Na/K dash around the surface, when Na/K reacts with water?
The hydrogen produced in the reaction causes the ball to move around.
Observations: Potassium reacting with water
- reacts more violently than Na
- bubbles of H₂ gas
- melts into a shiny ball that dashes around the surface
- enough heat produced so hydrogen burns with a lilac flame
Properties of transition metals
- very high m.p.
- very high density
- hard, strong metals
- form coloured compounds
- more than 1 oxidation state
In Periodic Tables, where can you find the mass number of an element?
At the top of the element symbol.
In Periodic Tables, where can you find the atomic number of an element?
At the bottom of the element symbol.
What does the group number tell us?
How many valence electrons an element has can be seen with the group number.
What does the period number tell us?
The period number tells us how many electron shells an atom has.
Elements in the same group have similar properties. Why?
The number of valence electrons of elements in the same group are the same.
Where can metals be found on the Periodic Table?
On the left
Where can non-metals be found on the Periodic Table?
On the right
What are the types of isotopes called?
Radioactive isotopes and non-radioactive isotopes.
Use of radioactive isotopes?
- being able to find the date an object dates back to
- treating cancer in radiotherapy
