The Periodic Table Flashcards
Why are there an increase in metallic properties down a group?
The size of an atom increases down a group. Hence the valence electron is further away from the attractive force of the nucleus. The metallic atom hence loses valence electrons more easily down a group.
Why is there a decrease in metallic properties going across a period from left to right?
The number of protons increases across a period. Hence attractive forces between the nucleus and the valence electrons become stronger. It becomes harder for the atom to lose the valence electrons across the period.
What are group 0 elements?
Noble gases are unreactive and monoatomic.
Simple Molecular structures with low m.p and b.p.
they have a naturally full electron shell.
What is lithium’s reaction with water like?
Reacts vigorously to form LiOH and H2 (g), Li floats on water and effervescence of H2 (g) observed.
What are the observations for Na reaction with water?
Reacts VERY VIOLENTLY to form NaOH and H2(g).
Darts about surface of water quickly.
H2 may catch fire+combust
(DANGEROUS REACTION)
What is the reaction of K with water?
Reacts VERY VIOLENTLY to form KOH and H2(g).
Darts about on water surface very quickly.
H2 (g) catches fire and explodes LILAC/PURPLE FLAME
Describe a simple test to carry out to test the pH of a solution after alkali metals react with water and the gas evolved when that happens.
Add Universal Indicator, should turn green-purple.
Place a lighted splint into where the gas was evolved. If it is extinguished with a pop the gas is hydrogen.
What are group 7 elements?
HALOGENS. Diatomic covalent moleqs, powerful oxidising agents.
Describe trends down group 7.
Colours of halogens become darker down the group.
Reactivity of halogens decrease down the group.
M.p and b.p increase down the group.
