Chem. KAP - Bonding

Force of attraction that holds atoms or ions together to form a compound

Chemical Bond

What is the attractive bond between?

Nucleus of one atom/ion and the electron cloud of another atom/ion.

What rule is chemical bonding driven by? What does that rule mean?

Chemical bonding is driven by the octet rule, which states atoms lose, gain, or share VALENCE electrons to achieve the electron configuration of the closest noble gas.

Unfilled or partially filled valence orbitals are ______

Inherently Unstable

What does it mean to be unstable?

Possess high potential energy

How is stability reached?

Reducing potential energy

Bond type is determined by

Valence electrons of participating atoms

Name the bond: transfer of electrons between a metal and nonmetal

Ionic

Name the bond: Sharing of electrons between nonmetals/metalloids

Covalent

Name the bond: electron sea between metal atoms

Metallic

An atom that loses electrons to achieve an octet will form a

Cation

An atom that gains electrons to achieve an octet will form a

Anion

Ionic compounds involve

Metal ion and nonmetal ion; may also involve polyatomic ions

Anions and cations are attracted to each other by 

electrostatic forces

What are electrostatic forces

Coulombic forces

Forces of attraction between oppositely-charged ions

Ionic bonds

What are Coulombic charges

Charges between two charged forces

How do you write those equations for chemistry?

Ion formation of Element 1 + Ionic formation of Element 2 —> Combination of Elements —> Element Name

What is a lattice?

3-D system of points showing the positions of ions that make up the ionic compound.

T/F: A lattice is used for all bonds?

False—it’s only used for ionic bonds

The electrostatic (Coloumbic ions) between ions are very ____. 

Strong

Because the electrostatic (Coloumbic ions) between ions are very strong, ionic compounds are found in nature as

Crystalline solids

Because the electrostatic (Coloumbic ions) between ions are very strong, ionic compounds have

High melting and boiling points

Because the electrostatic (Coloumbic ions) between ions are very strong, ionic compounds are

hard, rigid, brittle (shatters not flatten)

What does it mean if something is brittle?

Shatter not flatten

Ionic compounds will conduct ___ when ____

Ionic compounds will conduct electricity when molten or aqueous (dissolved in water)

The smallest particle of a ionic compound is a

formula unit

The formula unit is the smallest particle of which kind of compound?

Ionic

Electrolyte

substance that conducts electricity when molten or in solution

What are Coloumbic Forces saying basically?

Opposites attract/pull, likes push

Why does the ionic compound have to be either dissolved in water or molten to conduct electricity? In other words, why won’t the dry salt conduct?

Charged particles must be in motion for the substance to conduct electricity. In the solid form, the ions are held in place and cannot conduct electricity. Molten/dissolved = not held in place so they CAN conduct at that point.

Metals characteristically have few ___ in their highest energy levels

Metals characteristically have few electrons in their highest energy levels

Because metals characteristically have few electrons in their highest energy levels, metals have

vacant orbitals (typically d and/or p orbitals)

The vacant orbitals can be ____, allowing valence electrons to ____. This is known as the ____.

The vacant orbitals can be occupied, allowing valence electrons to travel freely throughout the metal. This is known as the electron sea.

The electrons in metallic bonds are ____.

Delocalized

What do we mean we say the electrons in metallic bonds are delocalized?

We are saying they do not belong to any one nucleus

This chemical bonding results from the attraction between nuclei of metal atoms and the surrounding sea of electrons

Metallic

What is the reason for the high thermal and electrical conductivity of metals?

The freedom of electrons to roam in metals

T/F: Metals are lustrous (think metalloids)

True

Why are metals lustrous/shiny? (think metalloids)

They absorb a wide range of light frequencies.

T/F: Metals are malleable (think metalloids)…and what does that term mean?

True; can be hammered into thin sheets

T/F: Metals are ductile…and what does that term mean?

True; can be pulled into a wire

in the covalent bond, electrons are shared by the bonding atoms to achieve ____ for the atoms

Octets

compounds that consist of covalently bonded atoms are

Molecular compounds

The smallest particle of a molecular compound

Molecule

The smallest particle in a covalent bond

Molecule

The chemical formula for a molecular compound is the

Molecular formula

nonmetal elements and sometimes metalloids tend to form which kind of bond

Covalent

Because molecular compounds have relatively weak intermolecular forces between molecules, molecular compounds often exist as

gases or vaporize easily at room temperature

Because molecular compounds have relatively weak intermolecular forces between molecules, molecular compounds

Have relatively low melting and boiling points

Because molecular compounds have relatively weak intermolecular forces between molecules, molecular compounds

Are relatively soft if solid

Because molecular compounds have relatively weak intermolecular forces between molecules, molecular compounds

Are usually insoluble meaning they do not dissolve in water

A single covalent bond involves one ___ of electrons and thus includes ___ electrons

A single covalent bond involves one shared pair of electrons and thus includes two electrons

Lewis structures are depictions of molecules that show electrons as

Dots

T/F: In a Lewis Structure, shared pairs of electrons (bonds) are drawn between atoms in the form of lines, unshared/lone pairs are represented by dots on o ne atom only

True

What are the three exceptions for needed # of electrons (N)?

H = 2, Be = 4, B = 6

What do you do if something has a charge?

It depends—

1) If the question asks you to find the ION, add the opposite of the charge under “S” and bracket the final structure with the charge shown in the PT.

2) If the question isn’t asking about the ion, just proceed as normal.

How do you find the number of needed electrons?

N in NASE

How do you find the available number of electrons (# fo valence electrons for each atom)?

A in NASE

How do you find the number of share electrons between atoms?

S in NASE

How do you find the number of unshared pairs needed to get an octet?

E in NASE

What are resonance structures?

Structures that occur wen it is possible to write 2 or more valid Lewis structures for the same molecule or ion.

T/F: Double bonds are shorter than single bonds.

TRUE

Why are the two bonds in ozone the same length?

The actual bonds are delocalized, so the bonds are hybrid. Each bond spends about half its time being single and half its time being double.

What is the difference between Lewis Dot Diagram and Structural Formula?

Lewis shows pairs as dots and does not use lines, structural formula uses them as lines

What does VSEPR theory stand for?

Valence Shell Electron Pair Repulsion theory

What does VSEPR theory explain?

The 3d shape of molecules

What does VSEPR state?

Because electron pairs repeal each other, the molecular shape results from valence electron pairs position themselves as far apart as possible (109.5 degrees, not 90 degrees like in diagram)

How do you know if you need to alter the “S” in NASE and place brackets around the molecular geometry?

If the provided element has a + or - or if it says it is an ion.

What do lines imply?

Sharing, so covalence

What is electronegativity

The measure of an atom’s ability to attract bonding electrons

WHAT SHOULD YOU DO IN EVERY SINGLE TYPE OF BOND DETERMINING?

Check if the elements being combined are metals/nonmetals!!!!! If they are different, the bond is automatically ionic.

What does it mean if the difference in electronegativity is less than .36?

Nonpolar covalent

What does it mean if the difference in electronegativity is .36-1.7

Polar Covalent

Describe the trends in electronegativity difference in relation to bonds

Large electronegativity difference = ionic bond

Moderate electronegativity difference = polar covalent bond

Little to no electronegativity difference = nonpolar covalent

What are the diatomics?

I—>F, F—>N, H

Where are the bonding pairs of electrons in covalent bonds located?

Between the nuclei of the atoms sharing the electrons

When the pull of each nucleus for the electrons is equally strong, the electrons are shared equally and are located on average halfway between the two nuclei. This is a 

nonpolar covalent bond

When the pull of one nucleus is stronger than the other, electrons move towards the more electronegative nucleus. This is a

Polar Covalent Bond

The more electronegative atom requires a ___ charge

Partial Negative

The less electronegative atom requires a

partial positive charge

How do you indicate the partial charges?

The figure 8 type thing with a sign

T/F: Don’t draw dipole lines unless it is polar

True

When drawing, the least electronegative should be in ___

The least electronegative should be in the middle, with the exception of “H”

What is another name for dipoles

Dipole moments

Where do the dipoles point

The more electronegative

T/F: Just because an atom contains polar bonds, doesn’t mean it is a polar molecule

True

Polarity of a molecule depends on

1) The existence of polar bonds (if none of the bonds are polar, the molecule is nonpolar)

2) Shape of the molecule

3) Orientation of the polar bonds

Why are molecules nonpolar even with dipoles?

Dipoles could cancel.

Is water polar or nonpolar and why?

Polar; dipoles don’t cancel

What are the three types of geometries that, assuming equivalent dipoles, would lead to nonpolar molecules even when a bond is polar?

Triatomic linear, trigonal planar, tetrahedral

What is a polar bond?

A bond between two non-metals where electrons are shared unequally

In a polar bond, which atom will hold the electrons closer to itself

The more electronegative one

What is a nonpolar bond?

A non-polar bond is a covalent bond where electrons are shared equally?

High melting and boiling points

Ionic and metallic

Conduct electricity when melted

Ionic and metallic

Poor electrical conductors in all phases

Covalent

Many soluble in nonpolar liquids but not in water

Covalent

Low melting and boiling points

Covalent