⭐️Chemical Bonds Flashcards
When bonds BREAK
Energy absorbed, higher energy state, less stable
What are the 3 types of bonds?
Ionic, covalent, metallic
Ionic bond
TRANSFER of electrons from balance of 1 atom to balance of another, creating ions
Affinity vs electronegativity
Affinity=attraction e have when NOT bonded
Electronegativity= force of attraction and atom has when BONDED
Pauling’s scale of Electronegativity
0.0 (no pull, noble gases) to metals, nonmetals and then 4.0 (strongest pull, 7v smallest radius flourine)
If electronegativity diff>1.67?
Transfer of e, IONIC
If electronegativity diff
Sharing of e, COVALENT
How do you draw Cl when ionically bonded to Na
Na+ [Cl]-…an e moved from Na to Cl
Ionic compounds are held together by
STRONG electrostatic/electrovalent forces (+) and (-) opposite charges hold metal/nonmetal (usually) together
Ionic compound properties
HIGH MP (strong forces holding +/- together) Salts
Bonds
Results from the simultaneous attraction of electrons to 2 nuclei
On a periodic table, electronegativity
Increases across a row and increases up a column (like affinity/IE)
Ionic Solids
Poor conductors, brittle/cleavage, crystalline lattice/NO free moving ions)
Ionic Liquids
Good conductors, melted salt (break down crystalline lattice) OR dissolved in solution (aq)…free moving ions
Ionic bonds form when charges are…
Opposite and equal (Einstein conservation of energy) to form a shell with the noble gas configuration of the nonmetals period (nonmetals gain)
Empirical formula
Simplest whole # ratio by atoms, ionic compounds are only in empirical formulas, (C6H12O6>C1H2O1)
When forming an ionic bond, metals…
Lost electrons to non metals
Length of ionic compound
Add up 2 radii
Covalent bonds
Atoms SHARE a pair/pairs of e… forms MOLECULE
Bond length
B/w 2 nuclei, lies on bond axis
Bond axis
Connect 2 nuclei
Bond angle
Formed by 2 bond lengths
Equal sharing of electrons
NON POLAR molecule, symmetrical…diatomic, symmetrical, trigonal planar, tetrahedral
Diatomic molecule
NONPOLAR covalent bonds, form NONPOLAR covalent molecules (even dist of e), 2 atoms have same electronegativity/diff=0
Molecular formula vs Lois dot vs vs structural
Molecular= N2
Louis dot= Valence dots with circles showing bonds
Structural= Lines showing bonds (#IT NEEDS= #OF LINES) and other electron pairs on opposite ends to show even force/no repel (for non polar)
Symmetrical shape
POLAR covalent BONDS but molecule is overall NONPOLAR due to symmetry ex: H-Be-H
When bonds FORM
(Potential) Energy released, radius decreases, lower energy state, more stable
Trigonal Planar
EXCEPTION TO OCTATE, NONPOLAR symmetry, POLAR no symmetry/double bond on one side, flat, bond angle=120, 0 unshared e-pairs, ex: BH3
Tetrahedral
5 atoms 3D, bond angle=109
NONPOLAR symmetrical or POLAR non symmetrical (if 1-3 atoms replaced w another) 0 unshared e-pairs
Methane
CH4
Unequal sharing of electrons
POLAR molecule, no symmetry, extra e on central atom…linear, bent/v-shape, trigonal pyramid
Bent/v-shape
POLAR, bond angle= 104.5, ex: H2O (the large cloud on central O pushes the H’s together…more polar, smaller bond angle) 2 unshared e-pair
Trigonal pyramid
POLAR, bond angle=107, 4 atoms 3D, ex: NH3, 1 unshared e-pair
Trigonal pyramid vs trigonal planar
pyramid= unshared pairs of e, always POLAR
Planar=all pairs of e shared, no blob on top, wider bond angle, can be nonpolar
Coordinate covalent bonds
Central atom shares its UNSHARED PAIR of electrons w H+ (proton tht has no e)….ex: NH4+ (ammonium ion) SEE TABLE E OF POLYATOMIC IONS (NH3+H+>NH4+, H+ needs 2, shares the N’s pair of e)
Polar covalent bonds
e shared between 2 DIFFERENT atoms
Properties of covalent molecules
Soft, low mp, poor conductors, generally small (like butter!)
Non-polar molecules are only soluble in…
Non-polar solvents (benzene, ether) but INSOLUBLE in polar solvents ie H20
Network solids/marcromolecules
EXCEPTIONS to properties of other covalent molecules, HARD LARGE HIGH MP, but still poor conductors
List the 4 network solid exceptions
Diamond, graphite, SiC (Silicon Carbide), SiO2 (Silicon dioxide)
Hybridization
Mix of sublevels to account for # of bonds, ex: C (6, write out e config, 2 unshared pairs (s2p2)>hybridization (electron moves from S to P)>4 unshared pairs (sp3)
Linear
Bond angle=180, 0 unshared e-pairs, ex: HCl
Sigma (o)
Single bonds
Lie on bond axis
Strong
Pi
Made by 2 unhybridized p-orbitals
Lie above/below bond axis/parallel to bond axis
Weaker>easier to break>further from nucleus
When there are more bonds…
MORE BONDS, MORE ENERGY, CLOSER TOGETHER, HARDER TO BREAK
Double bond
Pi and sigma (doesn’t matter which is which)
Triple bond
Pi sandwiching a sigma
Polarity
Stronger pull on atom w higher en (partial negative charge), protons in nucleus exposed on positive end (partial positive charge), polarity causes molecule-ion attraction CAUSED BY UNEQUAL EN OR UNSHARED PAIRS OF E/UNEQUAL SHARING OF E
Molecule-ion attraction
Process of how dissolving occurs (ion+polar molecule=dissolve), ex: H2O+NaCl=NaCl (aq)
O end surrounds cation Na+ bc they’re partial neg
H surrounds anion bc they’re partial pos
…Free moving Na+/Cl- ions…GOOD CONDUCTORS
Flourine
Most electronegative
Dipole-dipole forces
Intermolecular forces between 2 polar molecules (DOTTED LINE)
Intermolecular
Between 2 MOLECULES
Intramolecular
Within the molecule COVALENT BOND
Pairs of electrons that bond 2 atoms in a molecule are called
Shared pairs (bonding pairs, covalent bonds)
Why do electrons in the outer levels of atoms in a molecule spread apart as far as possible?
To minimize repulsive forces (e repel each other)
How are hybridized orbitals in an atom similar?
They are degenerate (have equal energies)
How are hybridized orbitals in an atom different?
Directions in space (x y z axis)
When an sp3 orbital of 1 carbon atom overlaps that of another carbon atom, how many electrons do the two atoms share?
2 (1 pair)
How many hybrid orbitals can sp3, sp2, and sp have?
4, 3, 2 (add)
How does the double bond of CH2O (trigonal planar)affect the angle between the 2 single bonds?
The angle will be smaller than expected bc the double bond occupies more space then the single bond, pushing them together (
A ____ of electrons is formed when an orbital of one atom overlaps and orbital of another atom.
Shared pair
___ bonds are always formed by sideward or peaked overlap of unhybridized p orbital
Pi
In single, double, and triple bonds bw 2 carbons, one of the bonds is always a ___ bond
Sigma
Pi bonds break more easily than sigma bonds bc the electrons forming Pi bonds are (further from/closer to?) the nucleus
Further from
Single, double, and triple have how many shared pairs of electrons by 2 atoms?
Single=1 pair
Double=2 pair
Triple=3 pair
Hybridization of orbitals on carbon atom is (H single C triple N 2e)
Sp1 (NOT Sp3 bc the pi’s have to be unhybridized p-orbitals)
why does water have a bond angle of 104 and not 180?
2 unshared pairs of electrons at the oxygen push the hydrogens together, making it polar
TEST TIP
In NH3, the test might NOT show extra electons on N making it pyramidal so double check
EN increases/why…
Going right (^ nuclear pull) and doing up (less shielding effect, stronger nuclear pull) F, O, N
IMF’s
Dipole-dipole and hydrogen bonding, and London dispersion force
Hydrogen bonding
Dipole-dipole forces between hydrogen of a molecule and highly EN (F, O, N SPECIALLY HIGH EN) of other molecules, HIGHEST IMF, HIGHER MP/BP
Dispersion forces
Weak forces, magnitude increases with LESS DISTANCE and LAGER MOLECULE SIZE (more forces, more energy to break forces, down column, ^MP, ^SHIELDING EFFECT)
Metallic bonds
Cations in a sea of mobile electrons, great conductor, high mp, strong, tenacity (malleable/ductile)
Van Der Waals radius vs covalent radius
Not overlapping (non bonded side) bigger
The partially negative side of a polar molecule has a higher…
Electronegativity
Strongest>weakest bonds/conductivity?
1) Metallic (always good conductor)
2) Ionic (strong electrostatic forces, good cond when liquid)
3) Covalent (bad conductors)
Exceptions to octate
BeH2 (sp, linear, Be has 4 not 8)
BH3/BF3 (sp2, trig planar)
When they ask for the hybridization of the orbitals for a molecule with a triple bond…
Do NOT include p bonds (Sp3 becomes Sp1)
