Element vs. Compound

Table 1.

Chemical Formula Element or Compound?

Fe Element

C Element

Cl2 Element

FeCl2 Compound

CCl4 Compound

1. What does the subscript 2 indicate in Cl2?

• There are 2 Cl atoms.

2. What is implied if there is no subscript?

• There is only 1 atom present.

3. Classify C, Fe, and Cl as metals or nonmetals.

• C• Fe• Cl

nonmetalmetalnonmetal

4. True or False: “The formulas for elements never contain a subscript.”

• False: –Cl2 is an element, but it has a subscript

5. Would you expect the formula S8 to represent a compound or an element?

• Element

6. Why?

• There is only 1 type of atom present.

7. Classify as element or compound.

• Co• CsOH• NaBr• PF5

• CO• H2O• HCl

element compound• CaCl2

• Br2

• SiO2

• P4

• KCl• O2

• Ag

compound elementcompound compoundcompound elementcompound compoundcompound elementcompound element

Honors Chemistry 12/17/13

“It is quality rather than quantity that matters.” – Lucius Annaeus

DO NOW:

1. In your notes: What part of the atom contains almost all of the atom’s mass?

AGENDA:

2. Students will be able to describe the difference between an ionic and covalent compound by reviewing our worksheet.

HOMEWORK:

1. Finish book work from last week for tomorrow.

ANNOUNCEMENT:

1. Science club is meeting today!

In your textbook: read section 7.2 (starts on page 210) and answer the following questions:

On page 232: numbers 60, 62, 63, 64, 66, 67

8. What clues are given in chemical formulas to differentiate between an element and a

compound?

• Multiple capital letters

Notes

• Subscript number = number of each atom present• No subscript = 1 atom present

• Element: made up of only 1 type of atom–may have more than 1 atoms

Notes

• Diatomic Elements–2 atoms present–Only certain elements exist as diatomic

in nature• Uncle HOFBrINCl–H2 O2 F2 Br2 I2 N2 Cl2

Notes

• Compound: made up of more than 1 type of atom–May have metals or nonmetals or both

Ionic or Covalent Bond?

Table 2.

Ionic Compound Covalent Compound

ZnCl2 CCl4

Na2O P2O5

Fe2O3 N2O4

CuI NI3

1. The compound ZnCl2 is considered to be _____ compound.

• Ionic Compound

2. The compound that contains N and O is a ______ compound.

• Covalent Compound3. Does the classification appear to be

based on how many atoms are present?

• No.

4. Write the symbols for each element present in Table 2.

Ionic CovalentZnCl2 CCl4

Na2O P2O5

Fe2O3 N2O4

CuI NI3

Zn

ClNaO

Fe CuI

CPN

• Ionic = metal + nonmetal• Covalent = nonmetal + nonmetal

6. Classify as ionic or covalent.

• NaBr• OF2

• CsF2

• SF6

• NO2

• CrCl3

ioniccovalent

• CoBr2

• BaS• CO2ionic

covalentcovalentionic

ionicioniccovalent

Notes

• Ionic Compound = a compound with a bond between a metal and a nonmetal

• Covalent Molecules = a compound with a bond between 2 or more nonmetals

Octet Rule

• Atoms tend to gain, lose, or share electrons so that they have 8 electrons in their outershell.

1. Potassium has ____ valence electrons.a. To achieve the octet rule, it would

be easier for potassium to ___________ electrons. (gain/lose)

b. This would make potassium a _____________. (cation/anion)

c. This is the symbol for potassium’s ion: _________

1

lose

cation

K1+

2. Magnesium has ____ valence e-s.a. To achieve the octet rule, it would

be easier for magnesium to ___________ electrons. (gain/lose)

b. This would make magnesium a _____________. (cation/anion)

c. This is the symbol for magnesium’s ion: _________

2

lose

cation

Mg2+

3. Boron has ____ valence electrons.a. To achieve the octet rule, it would

be easier for boron to ___________ electrons. (gain/lose)

b. This would make boron a _____________. (cation/anion)

c. This is the symbol for boron’s ion: _________

3

lose

cation

B3+

4. Nitrogen has ____ valence electrons.a. To achieve the octet rule, it would

be easier for nitrogen to ___________ electrons. (gain/lose)

b. This would make nitrogen an _____________. (cation/anion)

c. This is the symbol for nitrogen’s ion: _________

5

gain

anion

N3-

5. Oxygen has ____ valence electrons.a. To achieve the octet rule, it would

be easier for oxygen to ___________ electrons. (gain/lose)

b. This would make oxygen an _____________. (cation/anion)

c. This is the symbol for oxygen’s ion: _________

6

gain

anion

O2-

6. Chlorine has ____ valence electrons.a. To achieve the octet rule, it would

be easier for chlorine to ___________ electrons. (gain/lose)

b. This would make chlorine an _____________. (cation/anion)

c. This is the symbol for chlorine’s ion: _________

7

gain

anion

Cl1-

7. Why are noble gases inert?

• Reactions are movements of electrons.• Noble gases already have 8

valence electrons.• They don’t need to interact

with any other elements.

8. What’s the relationship between the charge of an ion and its location in the

periodic table?

• Elements in the same group tend to have the same charges for their ions.

Where do the electrons go …when an atom loses an

electron?

To another ATOM!

Where does the electron come from….

when an atom gains an electron?

From another ATOM!

Ionic Bonding

• A bond formed between 2 ions by the transfer of electrons

Ionic Bonding

• Usually between a metal and a nonmetal–Metals lose electrons –Nonmetals gain electrons

http://www.youtube.com/watch?v=5IJqPU11ngY

Ionic Bonding

Ionic Bonding

Ionic Bonding

Lewis Dots and Ionic Bonding