Unit 1: KA1 Periodicity Flashcards
The periodic table arranges all chemical elements in extraordinary ways. Different types of chemical bonding, patterns and trends can be observed in their arrangement. This deck of flashcards covers everything in Key Area 1 (Periodicity) of Higher Chemistry: groups, periods, types of bonding and structure, covalent radii, ionisation energies, electronegativities and every past paper question (except the repetitive ones) on Periodicity. Hopefully, it'll help you just as much as it helped me. :))
How are elements arranged in the periodic table?
In order of increasing atomic number.
What does the periodic table allow chemists to do?
Make accurate predictions of physical properties and chemical behaviour for any element, based on its position.
What are features of the periodic table (arrangement of elements-wise)?
Groups
Periods
GROUPS in the periodic table?
Vertical columns within the table.
What do “Groups” contain?
Contain elements with similar chemical properties, resulting from a common number of electrons in the outer shell.
PERIODS in the periodic table?
Rows of elements arranged in increasing atomic number.
What do “Periods” demonstrate?
Demonstrates an increasing number of outer electrons,
Moves from metallic to non-metallic characteristics.
How are the first 20 elements in the periodic table categorised?
According to bonding and structure.
Name the categories that the first 20 elements of the periodic table are sorted into. [4 answers]
Metallic,
Covalent molecular,
Covalent network,
Monatomic
Metallic bonding occurs between atoms of —– elements.
The outer electrons are ———– (free to move).
This produces an ————- force of attraction between the positive —– —- and the negative ———– electrons.
This ———– ‘sea of ———’ allow metals to conduct electricity.
metal,
delocalised,
electrostatic,
metal ions,
delocalised,
delocalised,
electrons
Give examples of METALLIC bonding/structure.
Li,
Be,
Na,
Mg,
Al,
K,
Ca
Describe the COVALENT BOND.
When two POSITIVE NUCLEI (of two non-metal atoms) are held together by their common ELECTROSTATIC ATTRACTION FOR a shared pair of ELECTRONS.
COVALENT MOLECULES are small groups of atoms held together by STRONG ——– bonds INSIDE the molecule and WEAK intermolecular* forces BETWEEN the molecules.
COVALENT.
*Refer to KA2 for the
weak London Dispersion forces between molecules.
Give examples of COVALENT MOLECULAR bonding/structure.
Most of the discrete covalent molecules are diatomic elements:
H₂,
N₂,
O₂,
F₂,
Cl₂,
There are also larger covalent molecular elements:
P₄,
S₈,
Fullerenes (eg. C₆₀)
Why are most of the diatomic molecules GASES at room temperature?
The diatomic molecules have very small intermolecular (London dispersion) forces. There’s enough energy at room temperature to overcome these weak forces of attraction, hence the molecules separate from each other (resulting in gases).
Why are Bromine and Iodine (diatomic covalent molecules) solid and liquid at room temperature?
They’re bigger molecules –> have more electrons than smaller gas molecules.
Therefore the London dispersion (intermolecular) forces are much stronger between their molecules –> takes more energy (than available at room temperature) to separate them.
Explain why Sulfur has a higher melting point than Phosphorus.
Sulfur consists of S₈ molecules and phosphorus P₄. The sulfur molecules have more electrons than the phosphorus molecules and so have stronger intermolecular (London dispersion forces). This in turn means sulfur has a higher melting point than phosphorus.
What are MOLECULAR FORMS of Carbon?
Fullerenes (eg. C₆₀)
What are FULLERENES comprised of?
What can fullerenes also exist as?
A series of carbon atoms arranged in hexagons and pentagons.
These are joined to make a ball shape.
They can also exist as tube shapes called nanotubes.
Fullerenes are very large molecules and so lots of energy is required to separate them. True or False?
True
Fullerenes sublime (change from solid to gas) at around 600*C.
Covalent networks are large, rigid 3D arrangements of atoms held together by weak intermolecular forces. True or False?
False, covalent networks are held together by STRONG COVALENT BONDS.
Does it take lots of energy to separate the atoms in a covalent network?
Yes. Lots of energy is required to break the strong covalent bonds.
This explains why elements with covalent network structures have HIGH melting and boiling points.
Give examples of COVALENT NETWORK bonding/structure.
B,
C (diamond & graphite),
Si
Why doesn’t diamond conduct electricity?
In diamond, all the outer electrons of each carbon are used to make single covalent bonds with neighbouring carbon atoms (resulting in a giant covalent network).
There aren’t any unbonded (delocalised) electrons in the diamond structure and so diamond doesn’t conduct electricity.