2.2.6 Covalent bonding Flashcards
what does covalent bonding occur between?
between two non-metals
how is a covalent bond formed?
the negatively charged pair of e- is attracted to the positive charges of BOTH nuclei, this attraction overcomes the repulsion between the two positively charged nuclei (attraction is the bond)
in covalent bonding, are electrons transferred or shared?
covalent bonding is sharing electrons
what does the number of electrons needed to obtain a noble gas configuration correspond with exactly?
the number of covalent bonds an element forms
how many electrons are shared in a single bond? C-C
2
how many electrons are shared in a double bond?
4
how many electrons are shared in a triple bond?
6
what is bond energy?
the energy required to break one mole of a particular covalent bond in the gaseous states
what is the unit for bond energy?
kJ mol-1
what effect does bond energy have, on the strength of covalent bonds?
the larger the bond energy, the stronger the covalent bonds
apart from bond energy, what else can measure the strength of a covalent bond?
average bond enthalpy
what is average bond enthalpy?
the average amount of energy needed to break a specific type of bond, measured over a wide variety of different molecules
what is bond length?
internuclear distance of two covalently bonded atoms (it is the distance from the nucleus of one atom to another atom which forms the covalent bond)
the greater the forces of attraction between electrons and nuclei…
…the more the atoms are pulled closer to each other
what is the effect of greater forces of attraction between electrons and nuclei?
this decreases the bond length of a molecule and increases the strength of the covalent bond
the shorter the bond length…
the stronger the covalent bond
which bond is the shortest and the strongest? single, double or triple
triple
why are triple bonds the shortest and tf the strongest?
due to the large electron density between the nuclei of the two atoms
explain how electron density between the nuclei of the two atoms causes the covalent bond to be stronger
if there is a large electron density between the nuclei of the two atoms, this increases the forces of attraction between the electrons and nuclei of the atoms
as a result of this, the atoms are pulled closer together causing a shorter bond length, the increased forces of attraction also means that the covalent bond is stronger
what is a lone pair?
when an atom in a molecule has a pair of non-bonding electrons
what is expanding the octet rule?
being able to accommodate more than 8 electrons in the outer shell
what does it mean if the central atom is ‘electron deficient’?
it accommodates less than 8 electrons in the outer shell means than the central atom
what is a dative covalent bond also known as?
a coordinate covalent bond
what is an electron deficient atom?
an atom that has an unfilled outer orbital
