A&P CH2 PG10

What are chemical bonds?

Forces that hold atoms together to form compounds

Why do elements connect by bonding?

So that they become more stable and to form molecules needed for life.

What are two main types of bonds ?

1. Ionic bonds

2. Covalent bonds

What is an ionic bond?

The attraction between positive and negative ions.

T/F: ionic compounds are called salts.

True

What is an ion ?

An atom that has gained or lost electrons.

What are electrons?

Negatively charged subatomic particles

T/F: atoms become ions by gaining or losing electrons.

True

What are the two types of ions?

1. Cation

2. Anion

What is a cation?

Positively charged ion

Paw-sitive

How is a cation formed?

Formed when an atom loses electrons

What are examples of cations?

Sodium ion (Na+)

Calcium ion (Ca²+)

Potassium ion (K+)

Losing negative electrons makes the atom:

Postive

What is an anion?

Negatively charged ion

How is an anion formed?

Formed when an atom gains electrons

What is an example of an anion

Chloride ion (Cl–)

Fluoride ion (F⁻)

Gaining negative electrons makes the atom:

Negative

Why do ionic bonds form?

Because opposite charges attract.

Postive cations are attracted to negative anions

What happens when opposite charges bond?

Charges balance out so the compound has no net charge

What is an ionic compounds?

When cations and anions bond

What are examples of Ionic Compounds? Name 2.

Sodium Chloride [NaCl]

Potassium Chloride [KCl]

Calcium Phosphate [Ca3(PO4)2]

Ionic Bond Review:

1. Involves electron transfer

2. Produces ions

3. Bonds are based on charge attraction

What are Covalent Bonds?

Forms when two atoms share electrons

T/F: Covalent bonds form molecules, not salts.

True

Ionic bonds form salts.

What are the two types of Covalent bonds?

1. Nonpolar

2. Polar

What are Nonpolar Covalent Bonds?

Atoms share electrons equally. Neither atom has a stronger pull on electrons

When do you know Nonpolar bonds occur?

When two atoms are:

1. The same element

2. Have very similar electronegativity

What are examples of Nonpolar Bonds? Name three.

Hydrogen Gas (H2)

Nitrogen Gas (N2)

Oxygen Gas (O2)

Chlorine Gas (Cl2)

Why is Oxygen Gas (O2) Nonpolar?

Oxygen bonded to Oxygen (O2) means both atoms pull equally.

Notice the symmetry.

What are C—H Bonds?

C-H bonds (carbon-hydrogen bonds) are covalent chemical bonds that connect a carbon (C) atom to a hydrogen (H) atom.

Why is it important to remember C—H Bonds?

1. The Carbon—Hydrogen (C—H) bond is fairly Nonpolar

2. Molecules with many C—H bonds are usually nonpolar

What are examples of C–H bonds that are Nonpolar?

Lipids (fats)

1. Triglycerides

2. Phospholipids

3. Fatty Acids

Why are Nonpolar molecules important to remember?

1. They do not dissolve well in water

2. They form membranes and insulation (fats)

What are Polar Covalent Bonds?

Atoms share electrons unequally. One atom pulls electrons more strongly.

What is Electronegativity?

An atoms ability to attract electrons

T/F: if one atom is more electronegative, the bond is polar.

True, the bond does not have an equal pull, therefore making it a polar bond.

T/F: The electrons spend more time near the more electronegative atom

True

What are Examples of common Highly Electronegative Elements? Name 2.

1. Oxygen (O)

2. Nitrogen (N)

3. Fluorine (F)

4. Chlorine (Cl)

(O) or (N), 2 common Highly Electronegative Elements, pair with which atoms (name 2), to create polar bonds.

Oxygen or Nitrogen pairs with ____ or ____ to create polar bonds.

1. Hydrogen (H) or

2. Carbon (C)

What are examples of Polar Bonds?

1. O-H (water)

2. N-H (protein)

3. C-O

-Slight negative charge near O or N

-Slight positive charge near H

Why do Polar Bonds matter?

It allows Hydrogen binding which enabled

1. Water’s unique property

2. Protein folding

3. Enzyme activity

4. Transport of substances

Ionic vs Covalent Bonds?:

Electrons transferred

Ionic

Ionic vs Covalent Bonds?:

Forms molecules

Covalent

Ionic vs Covalent Bonds?:

Partial or no charge

Covalent

Ionic vs Covalent Bonds?:

Electrons shared

Covalent

Ionic vs Covalent Bonds?:

Forms ions

Ionic

Ionic vs Covalent Bonds?:

NaCl

Ionic

Ionic vs Covalent Bonds?:

Weak in water

Ionic

Ionic vs Covalent Bonds?:

H2O

Covalent

Quick memory cues:

Polar

1. Polar

2. Unequal sharing

3. O & N involved

Quick memory cues:

Nonpolar

1. Nonpolar

2. Equal sharing

3. Same elements

Quick memory cues:

Covalent

1. Covalent

2. Sharing electrons

3. Molecules

Quick memory cues:

Ionic

1. Ionic

2. Ions

3. Cation/anions

4. NaCl

T/F: covalent bonds create ions

False. That's ionic bonds

T/F: C—H is mostly nonpolar

True.

What's the difference between polar bonds and ionic bonds?

polar bonds involve unequal sharing of electrons,

while ionic bonds involve a complete transfer of electrons