6 PERIODIC TRENDS Flashcards
what is the period table
list of elements arranged in order of increasing proton (atomic) numbers.
how many periods and groups are in the pt
7 periods and 18 groups of elements.
what is Elements from Group 3 to 12 are known as
Elements from Group 3 to 12 are known as transition metals or transition metals
what doe sthe group represent
number of valence electrons
what doe sthe period represent
number of principal quantum shells
how to identify metals and non metals on the pt
Step-like line from the top of Group 13 to the bottom of Group 16 divides the elements into metals and non-metals.
what oxides do metals form
Metals form basic oxides.
what oxides do non-metals form
Non-metals form acidic oxides.
what oxides do metalloids form
Metalloids form amphoteric oxides.
Similarity within the same Group
Elements in the Group:
- Have the same number of valence electrons
- Have the same chemical properties
- Forms ions with the same charges
- Form compounds with similar formulae
properties of elements Down the Group
Down the Group
- Atomic size increase
- Number of principal quantum shells increases
- Reactivity and metallic character increases down a group of metals
what are alkali metals
group 1 elements
Physical Properties of Alkali Metals
- Relatively soft and can be cut easily with a knife.
- Low melting and boiling points (compared to other metals).
- Good conductors of heat and electricity.
Change in Physical properties Down the Group (G1):
- _M_elting points and boiling points decrease down the group.
- _A_tomic radii of Group 1 metals increase down the group.
-
_D_ensity of alkali metal increases down the group.
MAD
why does Atomic radii of Group 1 metals increase down the group. and its link to shielding effect
Each Group 1 metal has an increase of 1 core electron shell, hence the shielding effect increases down the group
whats a nuclear charge
The protons in the nucleus exert an attractive force on the negatively charged electrons.
its number is the same as proton/atomic number
whats the shielding effect:
basically more core shells mean more INNER ELECTRONS, the OUTER ELECTRONS in the outer shells will have a weaker nuclear attraction
y is Group 1 are more reactive
they lose their valence electron more easily cuz atomic radii increases by 1 core electron shell -> valence electrons become** further** from the nucleus -> shielding effect increase -> it increases more than the nuclear charge -> effective nuclear charge decreases -> electrostatic forces of attraction between the nucleus and the valence electron becomes weaker. Less energy is required to remove
y does Density of alkali metal increase down the group.
the atomic mass(proton number) increases faster than the atomic volume.(no. of shells)
what g1s r less dense or more dense than water
Less dense than water: Li, Na and K
Denser than water: Rb and Cs
y does Melting points and boiling points decrease down the group.
- Size of metal cation increases down the group.
- Electrostatic forces of attraction between sea of delocalised electrons and metal cations decreases.
- Metallic bonding weakens down the group, less energy required to break the weaker metallic bonds,
Chemical Properties of alkali metals
- Group 1 elements are the most reactive metals in the Periodic Table.
- They have similar chemical properties because all the elements have similar electronic configuration, that is, one electron in their outermost shell.
- The Group I metals are very reactive. They react rapidly with air and vigorously with water. They are kept under oil to prevent them from coming into contact with air and water.
- They are called alkali metals as they react readily with water to form alkalis.
what happens when grp 1 mix w cold water
All the alkali metals react with cold water to form alkalis (soluble metal hydroxides) and hydrogen gas.
grp 1 low density metals showing a trend in melting point
as density increases, melting and boiling points tend to decrease.
(idk if need memorise all the numbers but this the trend other than potasssium)
reaction of water + Li
Reacts quickly with cold water.
Li floats on the water.
No flame is seen.
Effervescence is produced.
reaction of water + K
Reacts violently with cold water.
K melts and burns with a lilac flame and explodes.
Effervescence is produced.
reaction of water + Na
Reacts very quickly with cold water.
Na melts and burns with a yellow flame.
The molten sodium darts around the surface of the water.
Effervescence is produced.
what are halogens
grp 17
