Bonding Flashcards
a metal loses an electron to become a/an…
cation
what are the 3 main types of chemical bonds?
Ionic, covalent and metallic
a non metal gains an electron to become a/an…
anion
what is an ionic bond?
an electrostatic force of attraction between oppositely charged ions
the strength of an ionic bond depends on…
1) the charges of the ions
2) the ionic radiuses - small ions = sharper force of attraction
what are the 3 main properties of ionic compounds/crystals?
1) High melting + boiling points - lots of energy required to break the strong electrostatic forces of attraction between ions of different charges
2) Electrical conductor when molten - ions can move freely
3) Brittle - Repulsion will break the lattice structure apart
what is dative covalent bonding?
a covalent bond where all the donated electrons come from the same atom (symbolised by an arrow)
what is required for a dative/coordinate bond to form?
an electron deficient molecule
a molecule with a lone pair of electrons
name some of the properties of covalent molecules
non-conductors of electricity - no ions/delocalised electrons
low melting + boiling points - weak intermolecular forces between molecules
HOWEVER, Giant covalent/giant macromolecular structures have high ones because they have strong covalent bonds
what is electronegativity?
the power of an atom to attract electrons in a covalent bond
what is the Pauling scale and what is its range?
the Pauling scale measures the power of an atom to attract electrons in a covalent bond. it ranges from 0 - 4.
what happens to electronegativity when you go across and down the periodic table?
across - increase as nuclear charge increases
down - decrease as shielding increases
What are the three types of intermolecular forces, in order of strength?
van Der Waal’s forces
Dipole-dipole forces
Hydrogen bonding
What is a polar covalent bond?
A covalent bond where the electron density is unequally distributed.
A non-polarised molecule has a ______ distribution of electron density
Equal
How can electronegativity be used to predict types of bonding in compounds?
Biggest difference = ionic
Medium difference = polar covalent
Lowest difference = covalent
What does the Delta used in polar bonds mean?
Electron deficient or partial positive/negative
What does polarise mean?
Electron density is unevenly distributed
Or
Electron cloud is distorted
What determines the strength of van der waals forces?
Mr
Number of electrons in its molecule
Why are most metals ductile?
They are arranged in layers of ions
Layers of ions can slide over each other
What determines the strength of a polar bond?
Difference in negativity
-bigger = stronger
An example of temporary dipoles are…
van Der Waals forces
