Chapter 3 - Bonding Flashcards
How are Chemical Bonds formed?
When electrons are shared/transferred between 2 atoms to obtain a full outer shell, making it more stable
What are Ionic Bonds?
Ionic Bonds is the electrostatic force between 2 oppositely charged ions (Metal and Non-Metal)
The ions are formed when they transfer electrons to each other to become stable
What do a collection of Ionic Bonds form?
Giant Ionic Lattices/Crystals
What Ions do Metals make and why?
What ions do Non-Metals make and Why?
Positive ions as they donate electrons so they have more protons > electrons
Negative ions as they receive electrons so they have more electrons > protons
What are Covalent Bonds?
The attraction between the + Nuclei’s and the shared pair of electrons in overlapping orbitals (Non-Metal + Non-Metal)
Note: Orbitals usually contain 2 electrons, so sharing 2 electrons creates a full orbital which increases stability
What are Covalent Bonds proportional to?
The amount of orbital overlap
What are Dative/Coordinate Covalent Bonds?
Covalent bond where an atom with an unpaired electron shares the pair with a vacant atom
E.g. NH3 and H+ = NH4+
How are Dative/Coordinate Bonds shown?
With arrows showing where the pair of electrons is shared with
What is a Metallic bond?
The electrostatic forces between electrons and positive metal ions in a regular lattice
3 Factors Affecting the Strength of a Metallic Bond
More Protons, more nuclear attraction means stronger bond
More delocalized electrons, increase the strength of the bond
Smaller Atom, increase nuclear attraction which strengthens the bond
What are Ionic Crystals?
A solid consisting of many Ionic Bonds
3 Properties of Ionic Crystals
High Melting/Boiling point due to strong electrostatic forces
Conduct when molten/in aqueous as bonds break creating ions acting as charge carriers
Brittle and Soluble
What are Macromolecular Covalent Crystals?
Giant molecular Structures containing several Covalent Bonds in a regular lattice
Example: Diamond and Graphite
What are Allotropes?
Different forms of the same element
What are Simplemolecular Covalent Crystals?
Molecules containing a little amount of covalent bonds, intermolecular, vdw, hydrogen, permanent dipole forces
Low melting/boiling point and poor conductors
Examples: I2, H2O, Ice, CO2
What is electronegativity?
The ability to attract electrons more than other atoms within a covalent bond
Trends/Factors affecting Electronegativity
Increases across a period as if the amount of Protons increase, it will pull electrons in shells closer to it, decreasing the atomic radius
Decrease down a group as atomic radius increases as electrons in shells repel each other
Note: Electronegativity decreases down a group as Atomic Radius overrides the increase in Protons
What is polarity?
A property determining whether a covalent bond has an even/uneven distribution of electrons
What are Polar Bonds?
When there’s an uneven distribution of electrons, so there’s a + and - side, due to difference in electronegativity
Note: Polar is all bonds are identical, no lone electron pairs
What are Non-Polar Bonds?
When electrons are distributed evenly, so everything is either symmetrical or nothing is more electronegative
Symmetrical Molecules: CO2 is symmetrical as it has double bonds which cannot move, whereas H2O isn’t symmetrical as it has single bonds which can rotate
What is Polarization?
How strong partial charges on a molecule are
Note: If polarization is big enough, electrons may transfer. In Covalent Bonding sharing means elements have similar electronegativity
What is Polarization dependent on?
Difference in electronegativity, greater it is, the greater the charges are, increasing reactivity
What are Van der Waal Forces?
Transient/Induced Dipoles between molecules.
As electrons move randomly, theres a change for them to become unevenly distributed to create a temporary weak dipole that effects neighboring molecules to have the opposite charge to it
3 Factors affecting Vdw Forces
More outer electrons, higher chance to become dipole, creating stronger vdw and high melting/boiling point
Increasing Atomic Radius, electrons can move easier to create vdw forces easier
Greater Area of Surface contact, creates more Vdw as theres more neighboring molecules increasing Melting/Boiling point
What are Permanent Dipole-Dipole Forces?
Weak Electrostatic Force between opposite partial charges on 2 polar molecules
Example: HCL/NF
What are Hydrogen Bonds?
An electrostatic force between hydrogen. Strongest out of the 3 and have the highest melting/boiling point
