8: Covalent Bonds Flashcards
What is a covalent bond and how does it form?
A covalent bond is the electrostatic forces of attraction between the positively charged nuclei of the two bonded atoms and the negatively charged shared electrons. It forms when two atoms share a pair of electrons.
Are covalent bonds directional and why?
Yes; the bond acts solely between the two atoms involved in the bond.
How can the bond between hydrogen atoms in a hydrogen molecule be represented?
The covalent bond is made up of one bond pair of electrons, or one pair of shared electrons. The single covalent bond between the hydrogen atoms are represented by a single line H-H.
What is a lone pair of electrons?
A lone pair of electrons is a pair of electrons in the outermost shell of one of the atoms in a molecule which is not involved in bonding.
How are double bonds and triple bonds formed and represented?
A double bond results when two pairs of electrons are shared between two atoms in a molecule. It is represented by two lines (eg. oxygen: O=O)
A triple bond results when three pairs of electrons are shared. It is represented by three lines (eg. nitrogen: N≡N)
What is the name of the compound with chemical formula SO3?
Sulphur trioxide
What is the name of the compound with chemical formula NF3?
Nitrogen Trifluoride
What is the name of the compound with chemical formula N2O4?
Dinitrogen Tetroxide
What are two common types of models used to represent the shapes of molecules?
Ball-and-stick models and space-filling models
When is a covalent compound formed and when is an ionic compound formed?
When a metal combines with a non-metal, an ionic compound forms. When different non-metals combine, a covalent compound forms.
What is a dative covalent bond?
A dative covalent bond is a type of covalent bond in which both electrons come from the same atom.
What are the requirements needed to form a dative covalent bond?
- One atom having a lone pair of electrons
- A second particle having a vacant site in its outermost shell to accept the lone pair (ie. an electron-deficient chemical species).
What is relative molecular mass?
For an element or a compound existing as discrete molecules, the relative molecular mass is the sum of relative atomic masses of all atoms which make up the molecule. (for covalent compounds)
What is formula mass?
Formula mass of an ionic compound is the sum of the relative atomic masses of all the atoms in one formula unit of the compound.
