CHAPTERS 3.1-3.5 Flashcards
what is a single covalent bond?
the covalent bond formed when atoms share two electrons, one from each atom.
eg. hydrogen (two hydrogen atoms share one electron to form a single covalent bond)
what is a double covalent bond?
when two electrons are shared between atoms
eg. oxygen (each oxygen atom requires two electrons to gain a stable outer shell so when one oxygen bonds to another, each atoms shares two of its electrons)
what is a triple covalent bond?
when three electron pairs are shared between two atoms.
eg. nitrogen (when a nitrogen atom bonds with another, each atom contributes three electrons to the bond that forms because nitrogen requires three electrons to gain a stable outer shell)
what is a lewis structure (electron dot structure)?
it is a diagram used to represent molecules. it shows the valence shell electrons of an atom, as only these electrons are involved in bonding
what are polyatomic molecules?
molecules made up of more than two atoms.
eg. water (H2O), methane (CH4), ethene (C2H4)
what is the valence shell electron pair repulsion theory and what does it do?
it is a model used in chemistry to predict the shape of molecules. It states that electron pairs in the valence shell of an atom repel each other, causing them to arrange themselves to minimise this repulsion. by following this theory, chemists can determine the molecular geometry
what is an example of a tetrahedral molecule?
methane (CH4)
electron groups: 4
lone pairs: 0
what is an example of a pyrimidal molecule?
ammonia (NH3)
electron groups: 4
lone pairs: 2
what is an example of a bent molecule?
water (H2O)
electron groups: 4
lone pairs: 4
what is an example of a linear molecule?
hydrochloric acid (HCl)
electron groups: 4
lone pairs: 6
what is a non polar bond? give an example.
bonds with an equal distribution of bonding electrons (no charge on either end of the bond)
eg. H2, O2, N2
what is a polar bond? give an example
bonds with an imbalanced electron distribution
eg. CO2, HCN, PH3
what is a dipole?
the separation into positive and negative charge as they have two oppositely charged poles at each end of the molecule
how do you determine a covalent bond?
when the electronegativity difference between two atoms is zero (bond is also non polar)
what happens to the polar nature of a bond between two atoms as the electronegativity between the atoms increases?
it increases.
what are symmetrical molecules?
molecules that contain polar bonds that are evenly distributed. they are non polar, as the bond dipoles cancel each other out
what are asymmetrical molecules?
molecules that contain polar bonds and are polar molecules. a net dipole is created in the molecule
what is an example of a non polar molecule?
methane
what is an example of a polar molecule?
chloromethane
what are intermolecular forces?
forces of attraction or repulsion that act between neighbouring particles (atoms, molecules, or ions).
what is a dispersion force?
forces that exist between all molecules, whether they are polar or non polar.
what is a dipole dipole attraction?
it occurs between polar molecules. these forces result from the attraction between the positive and negative ends of the polar molecules
what is hydrogen bonding?
a strong form of dipole dipole attraction. only occurs between highly polar molecules in which one of the molecules has a hydrogen atom covalently bonded to a nitrogen, oxygen or fluorine atom
what is an allotrope?
the several different structural arrangements in the atoms of some elements. different forms of the same element
