Periodicity Flashcards
Describe intramolecular bonding
bonding within a molecule
intermolecular bonding
Bonds between molecules
london dispersion forces
forces of attraction that can operate between all atoms and molecules
What are london dispersion forces formed as a result of
electrostatic attraction between temporary dipoles and induced dipoles caused by the movement of electrons in atoms and molecules
What is a temporary dipole
the momentary difference in charge
How is an induced dipole created
the temporary dipole repels the electrons in the neighboring atom and they move to the side furthest away creating an induced dipole
What is the relationship between number of electrons and strength of london dispersion forces
as the number of electrons increases the strength of the london dispersion forces increases
What is covalent radius
a measure of the size of an atom
why does atomic size decrease across a period
because there is an increase in nuclear charge which pulls electrons closer to the nucleus
why does atomic size increase down a group
because the number of energy levels increases
What is the first ionisation energy
the energy required to remove one mole of electrons from one mole of gaseous atoms
Why does the first ionisation energy decrease down a group
the number of energy levels increases which leads to increased shielding
the electrons are further from the nucleus so have less attraction towards the nucleus so less energy is required to remove them
Why does the first ionisation energy increase across a period
the increased nuclear charge holds the electrons in the outer energy level more tightly
Why is the differnece in ionisation energys so great
the electron is removed form an energy level closer to the nucleus and is mroe strongly attracted to the nucleus
What is electronegativity
the measure of the attraction an atom involved in a bond has for the electrons in a bond
Why does electronegativity increase across a period?
the increased nuclear charge increases the attraction for the bonding electrons
ionisation energies have a positive value state what this indicates
its an endothermic process
State what having a high electronegativity value indicates
there is a string attraction for bonding electrons
State what having a low electronegativity value indicates
there is a weak attraction for bonding electrons
explain why the first ionisation energy of potassium is less than sodium
more occupied energy levels so nuclear shielding is increased
In what ways does the structure of fullerene differ from other carbons graphite and diamond
fullerene is a molecule
graphite and diamond are networks
State which type of bonding and structure contains the elements with the greatest attract for electrons in a covalent bond
covalent molecular gases
An unknown element is found to have a melting point of over 2000 degrees but an oxide of this element is a gas at room temperature
what type of bonding is most likely to be present in the element
Pure covalent
What element will have 0 electronegativity
helium
