unit 1 Flashcards
(25 cards)
What is the arrangement of elements in the periodic table based on?
Increasing atomic number
What do groups in the periodic table represent?
Vertical columns containing elements with similar chemical properties
What do periods in the periodic table represent?
Rows of elements arranged with increasing atomic number
List the categories of the first 20 elements in the periodic table based on bonding and structure.
- Metallic (Li, Be, Na, Mg, Al, K, Ca)
- Covalent molecular (H2, N2, O2, F2, Cl2, P4, S8, fullerenes)
- Covalent network (B, C, Si)
- Monatomic (noble gases)
What is the covalent radius?
A measure of the size of an atom
What is the first ionisation energy?
The energy required to remove one mole of electrons from one mole of gaseous atoms
What factors explain trends in ionisation energies?
- Atomic size
- Nuclear charge
- Screening effect due to inner shell electrons
Define electronegativity.
A measure of the attraction an atom has for the electrons of a bond
What is a covalent bond?
A bond formed by the sharing of pairs of electrons between atoms
What characterizes polar covalent bonds?
Different attractions of the atoms for the pair of bonding electrons
What is an ionic bond?
The electrostatic attraction between positive and negative ions
What are van der Waals forces?
Attractive forces acting between molecules
What are London dispersion forces?
Forces of attraction between temporary dipoles and induced dipoles
What defines a polar molecule?
A molecule that has a permanent dipole
How do hydrogen bonds compare to covalent bonds?
Hydrogen bonds are stronger than permanent dipole interactions but weaker than covalent bonds
What properties are affected by hydrogen bonding?
- Melting points
- Boiling points
- Viscosity
- Solubility/miscibility in water
What results in the anomalous boiling points of ammonia, water, and hydrogen fluoride?
Hydrogen bonding
What is reduction in a chemical reaction?
A gain of electrons by a reactant
What is oxidation in a chemical reaction?
A loss of electrons by a reactant
What defines an oxidising agent?
A substance that accepts electrons
What defines a reducing agent?
A substance that donates electrons
Which group in the periodic table contains the strongest reducing agents?
Group 1
Which group in the periodic table contains the strongest oxidising agents?
Group 7
What is the electrochemical series?
A series of reduction reactions
