Atoms and Bonding

Valence Electrons

100

electrons involved in bonding between atoms are

valence electrons

200

when an atom loses an electron, it becomes a

positive ion

300

atoms tend to form bonds so that they have ___ valence electrons and become more stable.

8

400

Draw an electron dot diagram for Beryllium (Be). How many dots should be drawn around the element's symbol? Explain

2: elements in group 2 have 2 valence electrons.

500

How do Valence Electrons relate to the chemical reactions of an element?

Valence electrons are the electrons that are most loosely held by the atom and the ones that are involved in chemical reactions. Chemical reactions occur whenever valence electrons are shared or transferred between atoms. The number of valence electrons determines how these reactions take place and what kind of bonds atoms can form.

Ionic Bonds

100

Ionic compounds that dissolve in water conduct electricity because they break into _________ that move freely

ions

200

In the ionic compound, magnesium bromide, MgBr2, what does the 2 stand for?

2 bromine ions for every magnesium ion

300

In a chemical formula for an ionic compound, which item is written first?

the positive ion

400

how many elements of group 1 would be needed to react with group 16

2

500

Write a balanced chemical formula and name the compound formed between Potassium (K) and Oxygen (O)

K2O (K should have 2 as a subscript) Potassium Oxide

Covalent Bonds

100

ionic compounds form hard, brittle ______________

crystals

200

What is one property of molecular compounds?

Low melting point; low boiling point

300

how many electrons are shared in a double bond?

2 pairs or 4 electrons

400

Describe a nonpolar bond? Give 1 example.

A covalent bond when 2 atoms share electrons equally, like H2 gas.

500

Draw an electron dot diagram for water. What special properties does this structure provide?

H20...see pg 140 in textbook. This is a polar molecule, van der Waals forces attract water molecules to one another causing surface tension, cohesion...water to balloon up on a penny, allow a gecko to grip smooth surfaces (glass)

Misc.

100

which group contains the most stable elements?

noble gases

200

metals form this type of bond with nonmetals

ionic bond

300

Is Carbon Dioxide a polar or nonpolar molecule?

nonpolar. Because of its linear construction, the oxygen atoms pull in opposite directions in equal strength and cancel out, so the molecule is nonpolar.

400

Describe properties that would help you to distinguish an ionic compound from a molecular compound.

Ionic compounds have high melting points and high boiling points compared to molecular compounds. Ionic compounds that are dissolved in water or melted will conduct electricity. Molecular compounds do not conduct electricity in either case.

500

Compare a covalent bond and an ionic bond.

A covalent bond is formed when two atoms share valence electrons. Neither atom loses electrons or takes electrons from the other. No charged particles form. In an ionic bond, one or more electrons are transferred from one atom to another. Atoms that lose electrons become positively charged ions, and atoms that gain electrons become negatively charged ions. These oppositely charged particles then attract each other.