Alkali Metals and Halogens Flashcards
Which alkali metal is radioactive?
Francium
Physical properties of alkali metals:
The melting and boiling points of the elements decrease as you go down the group
The density of the elements increases as you go down the group
The metals become softer as you go down the group
They are shiny and silver but tarnish quickly
Storage and handling of alkali metals:
Na, Li, K: stored under oil
Rb, Cs: stored in sealed glass tubes
Why are alkali metals placed in the same group?
The same number of outer electrons
Similar chemical properties: forming hydroxides, oxides, ionic compounds, and compounds with halogens
Potassium produces enough heat in reaction with water to ignite hydrogen which burns with _________
A lilac flame
Why does the reactivity increase as you go down the first group?
The reactivity depends on how easily they can lose their electrons. That depends on how strongly the nucleus attracts the electron
Color of alkali metal oxide:
White
Group 1 metal ions are ________ in color
White/colorless
Color of the dichromate ion and manganate ion
Dichromate ion: orange
Manganate ion: purple
Colors of halogens:
F₂ - Yellow
Cl₂ - Green
Br₂ - Red-brown liquid, orange/brown vapor
I₂ - Grey solid/Purple vapor
Safety when using halogens:
Handled in fume cupboards due to poisonous vapors
Bromine is corrosive so caution should be taken so that it doesn’t come in contact with the skin
Reactions of halogens:
Halogen + hydrogen ➡ Hydrogen halides (acidic, poisonous gases)
Hydrogen halides + Water ➡ Solutions of acids
Halogen + Alkali metals ➡ Salts
In redox reactions:
- The more reactive halogen is always ________
Reduced/stronger oxidizing agent
Why does the reactivity decrease as you go down the seventh group?
The reactivity of halogens depends on how easily they form negative ions.
A chlorine atom is smaller and so when an electron is added to the outer shell, it is more strongly attracted to the nucleus as compared to the halogens below it
