Covalent Bonds

Covalent bonds

The bond that is formed when 2 atoms have a similar ionization energies and electron affinities

Hydrogen molecule of two hydrogen atoms

Example of a covalent bond

2, electrons, stabilizing

When two hydrogen atoms bond covalently, then each atom has _ _________ ___________ the molecule.

neutral, weaker, ionic

The bonding in the covalent bond is _______, making them ______ than the _____ bonds

melting, boiling

Covalent compounds have a much lower _______ and _______ points than the ionic compounds.

liquids, gases

Many covalent compounds are _______ or _____ at the room temperature.

softer

When covalent compounds are in a solid state they are much ______ than the ionic solids.

insoluble, electrically neutral

Most covalent compounds are _________ in water because they are ____________________.

poor

Most covalent compounds are ____ conductors of electricity in any state.

Bond length

Determined by the distance at which the lowest potential energy is achieved.

electrons, atomic nuclei

Valence orbitals of hydrogen atoms overlap more they come close to each other.

Single _________ on each hydrogen atom interacts with the _____________ occupying the space around both the atoms.

stabilizes, decreases, decreases

Strong attraction of each shared electron to both nuclei __________ the system.

Potential energy _________ as the bond distance _________.

repel, increases

If the 2 hydrogen atoms continue to approach each other;

The positive charges in the 2 nuclei begin to _____ each other, and potential energy _________.

Endothermic process

The process where energy gets added to break chemical bonds.

Exothermic process

The process when energy gets released to form chemical bonds.

436 kJ

The amount of energy that is required to break the hydrogen molecule into 2 hydrogen atoms in 1 mole.

-436 kJ

The amount of energy that gets released when two hydrogen atoms form a single hydrogen molecule in one mole.

Pure covalent bonds

Atoms forming the bonds are identical

Electrons in these bonds are shared equally

Electrons shared in these bonds have an equal probability of being near each nucleus

Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, and Iodine

List of all the elements that exist as the diatomic molecules.

7

No. of valence electrons a chlorine atom has.

Polar Covalent bonds

The bonding electrons are unequally shared.

Bonding electrons are more attracted to one atom than the other atom, giving us a shift of electron density to that atom.

Gets characterized by partial positive charge on 1 atom and partial negative charge on the other

Happens with un identical atoms getting linked

negative charge

In the polar covalent bonds, the atom attracting the electrons more strongly, acquires the partial _______________.

Hydrogen Chloride (HCl)

One example of a Polar Covalent compound

chlorine, hydrogen, negative, positive

Electrons in the HCl bond spend more time near ________ atom than compared to ________ atom. In this molecule chlorine carries a partial, ________ charge and hydrogen carries a partial ________ charge.

Electronegativity

A significant property of the bonding atoms to determine if the bond is polar or nonpolar.

The measurement of the tendency of an atom to attract electrons towards itself

Determines how is the distribution of shared electrons is between two atoms in a bond.

A dimensionless quantity

Only calculated and not measured

Description of how tightly an atom attracts electrons in a bond.

The electronegative atom in the polar covalent bond

The atom that is stronger at attracting the electrons

Therefore, has a stronger electronegativity

Will be the one with a partial negative charge

Greater difference in electronegativity

Thing that results in:

More polarized electron distribution

Larger partial charges of atom

left, right, top, bottom

In a periodic table, electronegativity increases from ____ to _____ and decreases from ___ to ______.

Upper-right nonmetals

Types of elements that have the highest electronegativity

Fluorine (4.0)

The most electronegative element

Linus Pauling

The chemist who came up with the derived Electronegativity values for the elements

Alkali Metals

The family of elements that have the least Electronegativity

Noble gases

The family of electrons that is completely excluded from the Electronegativity values because they do not share electrons with other atoms as they have a full valence shell.

Xenon dioxide

An exceptional noble gas compound formed under the extreme conditions, which do not fit in the general model of Electronegativity

Electron affinity

A measurable physical quantity that says the amount of energy released or absorbed when the isolated gas-phase

kJ/mol

S.I. Unit of Electron affinity

The absolute value of the difference in electronegativity

Of two bonded atoms that provide a rough measure of the expected polarity in the bond, giving us the bond type.

ΔEN

Symbol that represents the absolute value of the difference in Electronegativity.

ΔEN < 0.4

The bond is pure covalent

ΔEN is between 0.4 and 1.8

The bond is polar covalent

ΔEN > 1.8

The bond is ionic

Hydrogen Fluoride

An exceptional compound to the general guide of Electronegativity, that has ΔEN = 1.9 and yet it is considered a polar covalent compound.

Ammonia

An exceptional compound to the general guide of Electronegativity, that has ΔEN = 0.9 and yet it is considered a polar covalent compound.

Sodium Chloride

An exceptional compound to the general guide of Electronegativity, that has ΔEN = 2.1 and yet it is considered an ionic compound.

Manganese(II)Iodide

An exceptional compound to the general guide of Electronegativity, that has ΔEN = 1.0 and yet it is considered an ionic compound.

Hydroxide, Nitrate, and Ammonium

Three examples of the polyatomic ions that are held together by polar covalent bonds.

potassium cation and Nitrate anion

The bonding in the potassium nitrate contains what?

Sickle cell anemia

An inherited disease wear red blood cells become misshapen, leading to blocked blood flow pain and anemia