Periodicity Flashcards
What is periodicity?
Periodicity is a regular periodic variation of properties of elements with increasing atomic number in the periodic table.
What way can trend exist in the periodic table?
You can see trend horizontally and vertically.
What does electron configuration determine?
Electron configuration determines the type of reaction.
What 3 things affect Ionisation energies?
- Nuclear charge
- Distance from Radius / Atomic Radius
- Electron shielding - number of shells.
What is the trend in ionisation energies ACROSS THE PERIOD?
- Nuclear charge increases
- Electron Shielding stays the same
- Atomic Radius decreases = stronger attraction between nucleus and electrons.
OVERALL: Energy needed to remove an electron increases.
What is the trend in ionisation energies DOWN THE GROUP?
- Number of shells increases = distance increases, so weaker forces of attraction.
- More shells = increased shielding, weaker attraction
- Increase in nuclear charge is outweighed by these factors.
THEREFORE, first ionisation energies decrease.
What is the ionisation energy?
This is the amount of energy required to remove one mole of electrons from one mole of gaseous atoms to form one mole of 1+ Ions.
What formula is used to express the first ionisation energy?
X(g) –> X+(g) + e-
What formula is used to express the second ionisation energy?
X+(g) –> X2+(g) + e-
What is the general trend from metals to non-metals across a period in the periodic table?
Elements change from metals to non-metals from left to right across a period.
Where does the metal to non-metal changeover occur in the periodic table?
The changeover occurs along a diagonal line from the top of Group 3 to the bottom of Group 7.
What are metalloids, and give examples?
Metalloids (or semi-metals) have properties between metals and non-metals. Examples: Boron (B), Silicon (Si), Germanium (Ge), Arsenic (As), and Antimony (Sb).
How does the metal/non-metal divide vary in Group 4?
Carbon (C) is a non-metal, while lead (Pb) is a metal. Silicon (Si) and germanium (Ge) are metalloids.
How many metals and non-metals exist in the periodic table?
There are 92 metals and 22 non-metals.
Why are non-metals significant despite being a minority in the periodic table?
Elements like carbon, hydrogen, nitrogen, and oxygen are crucial in organic chemistry and biochemistry.
What is the physical state of most metals at room temperature?
Most metals are solids at room temperature, except mercury (Hg), which is a liquid.
What is a common property of all metals?
All metals conduct electricity due to the presence of delocalised electrons.
What are some examples of metals with different properties?
Strong and hard: Tungsten (W)
Soft: Lead (Pb)
Light: Aluminium (Al)
Very heavy: Osmium (Os)
How does a metallic structure form?
Each metal atom donates its negative outer-shell electrons into a shared pool of delocalised electrons, allowing electrical conductivity.
What is metallic bonding?
Metallic bonding is the strong electrostatic attraction between cations (positive ions) and delocalised electrons.
What happens to cations in metallic bonding?
Cations are fixed in position, maintaining the structure and shape of the metal.
What is a giant metallic lattice?
A structure in which billions of metal atoms are held together by metallic bonding in a repeating pattern.
What are the key properties of metals?
Strong metallic bonds (attraction between positive ions and delocalised electrons)
High electrical conductivity
High melting and boiling points
Why does diamond have a high melting point?
Strong covalent bonds require a large amount of energy to break.
Why can metals conduct electricity in solid and liquid states?
Delocalised electrons can move freely through the structure, carrying charge.
Why does tungsten (W) have a very high melting point (3422°C)?
The metallic bonds in tungsten are very strong, requiring a large amount of energy to break.
Why does mercury (Hg) have a low melting point (-39°C)?
Weak metallic bonding in mercury requires less energy to break.
What are the exceptions to electrical non-conductivity in giant covalent lattices?
Graphene and graphite can conduct electricity due to free-moving electrons.
How does metallic bonding explain the high melting and boiling points of metals?
Strong electrostatic attraction between metal cations and delocalised electrons requires a large amount of energy to overcome.
What is a giant covalent lattice?
A structure where atoms are held together by a network of strong covalent bonds.
Are giant covalent lattices soluble? Why or why not?
No, because the covalent bonds are too strong to be broken by solvent interactions.
Give examples of elements that form giant covalent structures.
Carbon (in diamond and graphite) and silicon.
What is the structure of diamond?
A tetrahedral arrangement where each carbon atom is covalently bonded to four other carbon atoms.
Do metals dissolve in solvents? Why or why not?
No, because the strong metallic bonds cannot be broken by interaction with polar solvents.
What is the structure of silicon dioxide (SiO₂)?
A giant covalent structure similar to diamond, making it stable and generally unreactive.
Why do most giant covalent structures not conduct electricity?
All outer-shell electrons are involved in bonding, so no free electrons are available for conduction.
