Chemical Bonding

Covalent Bond

sharing of electrons (occurs between nonmetals)

Triple Bond

6 electrons (or 3 pairs of electrons) being shared between 2 atoms (made up of 1 sigma and 1 pi bond)

Polar Molecule (not the same as a polar bond)

If on the central atom there are lone pairs of electrons (also called unshared electrons) or electrons that are not involved in bonding the molecule will be polar (regardless of the bonds). The overall pull is uneven. Trigonal pyramidal and bent shaped molecules will always be polar molecules.

Nonpolar Covalent Bond

Equal sharing/pulling of electrons between nonmetals (if EN difference is 0, 0.1, or 0.2 assume it is a nonpolar covalent bond)

What information on the periodic table is used to complete electron dot diagrams?

The number of valence electrons is represented by the dots in the electron dot diagrams.

A force that holds atoms together is a chemical

bond

What is the most likely way in which an atom of magnesium (Mg) will satisfy the octet rule when it forms bonds?

by losing two electrons

Atoms of which elements form bonds without satisfying the octet rule?

helium (He) and hydrogen (H)

The electron dot diagram shows the arrangement of dots without identifying the element. Which element symbol's could replace the question mark in the diagram?

oxygen (O), sulfur (S), selenium (Se), and tellurium (Te)

How many dots belong in the electron dot diagram of a boron (B) atom?

three

What does the octet rule state that explains why atoms bond?

An atom bonds to have eight valence electrons to become stable.

Metal atoms tend to give away valence electrons when they bond with nonmetal atoms. What type of bond will form between the metal and nonmetal atoms and why does this bond form?

An ionic bond will form because electrons are transferred.

Fluorine (F) and bromine (Br) are in the same group on the periodic table. How do atoms of these elements compare when they form bonds?

Both a fluorine atom and a bromine atom gain one electron, and both atoms become stable.

An atom of lithium (Li) forms an ionic bond with an atom of fluorine (F) to form lithium fluoride. How are the valence electrons of these atoms rearranged to form this bond and what proportion is needed?

Electrons are transferred from the lithium atom to the fluorine atom. 1 lithium ion and 1 fluoride ion will form (LiF)

Sal drew the electron dot diagram of an aluminum atom. How should Sal correct his diagram?

He should add a single dot to the symbol.

Nonpolar Molecule (not the same as a nonpolar bond)

If on the central atom there are NO lone pairs of electrons (also called unshared electrons) the molecule will be nonpolar (regardless of the bonds). The overall pull is even.

Lead is malleable, so it can be pounded into flat sheets without breaking. How does the bonding within lead help to explain this property?

Metallic bonds involve many valence electrons shared by many atoms, so the bonds can move around as the metal is pounded.

linear shape (180 bond angle)

central atom hybridization is sp

trigonal planar shape (120 bond angle)

central atom hybridization is sp2

bent shape (close to 109.5 bond angle)

central atom hybridization is sp3

tetrahedral shape (109.5 bond angle)

central atom hybridization is sp3

trigonal pyramidal shape (close to 109.5 bond angle)

central atom hybridization is sp3

When sodium atoms (Na) and chlorine atoms (Cl) join to make sodium chloride, or table salt, they form an ionic bond. Using this information, which pair of elements is most likely to form an ionic bond?

metal and nonmetal

The electron dot diagram shows the arrangement of dots without identifying the element. Which element symbol's could replace the question mark in the diagram?

nitrogen (N), phosphorus (P), and arsenic (As)

Hybridization (hybrid orbitals)

sp, sp2, sp3

Based on the location of nitrogen (N) on the periodic table, how many additional electrons does a nitrogen atom need in its valence shell to satisfy the octet rule when it forms bonds?

three

Single Bond

2 electrons (or 1 pair of electrons) being shared between 2 atoms (also called a sigma bond)

Double Bond

4 electrons (or 2 pairs of electrons) being shared between 2 atoms (made up of 1 sigma bond and 1 pi bond)

Sunni drew an electron dot diagram of a silicon atom. In addition to changing the symbol to C, how would this diagram compare with an electron dot diagram of a carbon atom (C)?

The same number of dots would appear in the diagram for carbon.

The diagram shows an electron shell model of a sodium atom. How would the model change as the atom forms bonds?

The third shell would be empty so that the eight electrons in the second level would be outermost after the atom loses one electron.

Polar Covalent Bond

Unequal sharing/pulling of electrons between nonmetals (use electronegativity difference to determine if a bond is polar - if the EN difference is above 0.3 assume it is a polar covalent bond)