Unit 3 Lesson 3

Question 1

Chemical bond

Answer 1

An interaction that holds atoms or ions together

An atom forms bonds by gaining, losing, or sharing valence electrons

Question 2

Molecule

Answer 2

A group of atoms held together by chemical bonds

Question 3

What happens to atoms during a chemical change?

Answer 3

Atoms are not created or destroyed. They are just rearranged

When atoms are rearranged, chemical bonds are formed or broken

Question 4

Models of atoms

Answer 4

Electron cloud model - shows how electrons are in the electron cloud but doesn’t show the # of electrons

Bohr model - shows the # of electrons as dots in rings around the nucleus. Each ring represents an energy level

Space-filling model - atoms are shown as solid spheres

Question 5

Bohr model

Answer 5

Shows electrons in rings called energy level

Each energy level can hold a specific # of electrons
1st level - can hold up to 2
2nd level - can hold up to 8

Question 6

Valence electrons

Answer 6

Electrons found in the outermost energy level of an atom

Question 7

How does the period table show the # of valence electrons?

Answer 7

Elements in the same group have the same # of valence electrons

In groups 1 and 2 the group # is the same as the # of valence electrons
In groups 13-18, the # of valence electrons is the same as the last digit

Question 8

Why do atoms form bonds?

Answer 8

An atom forms bonds if its outermost energy level is not full of electrons

Forming bonds allows atoms to fill the outermost energy level