Unit 3 Lesson 3 Flashcards
Chemical bond
An interaction that holds atoms or ions together
An atom forms bonds by gaining, losing, or sharing valence electrons
Molecule
A group of atoms held together by chemical bonds
What happens to atoms during a chemical change?
Atoms are not created or destroyed. They are just rearranged
When atoms are rearranged, chemical bonds are formed or broken
Models of atoms
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
Bohr model
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
Valence electrons
Electrons found in the outermost energy level of an atom
How does the period table show the # of valence electrons?
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
Why do atoms form bonds?
An atom forms bonds if its outermost energy level is not full of electrons
Forming bonds allows atoms to fill the outermost energy level