How do elements join together to form chemical bonds? Electrons and Energy Levels How is an electron’s energy related to its distance from the nucleus? Why do atoms gain, lose, or share electrons? Chapter Introduction

Lesson 1 Reading Guide - Vocab Survey Term Place a check mark for your choice. 1 -I’ve never seen or heard this word   2 -I’ve seen or heard this term but don’t know what it means. 3 -I know this term but can’t fully explain it or give an example 4* -I can totally explain this and give an example *If you mark 4 tell me what you know about this term Chemical bond Valence electrons Electron dot diagram period group Lesson 1 Reading Guide - Vocab

Atoms Bond A chemical bond is a force that holds two or more atoms together in a compound. Draw a lithium-7 atom Label protons, neutrons, and electrons. List the charge of each. Lesson 1-2

Atoms Bond (cont.) 3. An electron moves around the nucleus at a distance that corresponds to its amount of energy. Lesson 1-2

4.Areas of space in which electrons move around the nucleus are called energy levels. 5. Electrons closest to the nucleus have the least amount of energy. Electrons farthest from the nucleus have the greatest amount of energy. Lesson 1-2

Atoms Bond (cont.) 6. The attraction between the positive nucleus of one atom and the negative electrons of another atom is what creates a chemical bond. 7. A valence electron is where? Lesson 1-2

8. The periodic table can tell you how many valence electrons an atom has. Renumber your periodic table with A and B groups Lesson 1-2

Atoms Bond (cont.) 9. In 1916 an American chemist named Gilbert Lewis developed the electron dot diagram, a model that represents valence electrons in an atom as dots around the element’s chemical symbol. Lesson 1-2

Atoms Bond (cont.) 10. Atoms with eight valence electrons are chemically stable and do not easily react with other atoms. With the exception of helium, noble gases have eight valence electrons and are chemically stable. 11. Atoms that have between one and seven valence electrons are reactive or chemically unstable and easily bond with other atoms to form chemically stable compounds. Lesson 1-2

Atoms Bond (cont.) Why do atoms gain, lose, or share electrons? Lesson 1-2

A) Electrons are less strongly attracted to a nucleus the farther they are from it, similar to the way a magnet attracts a paper clip. Lesson 1 - VS

B) Electrons in atoms are in energy levels around the nucleus B) Electrons in atoms are in energy levels around the nucleus. Valence electrons are involved in chemical bonding. Lesson 1 - VS

C) All noble gases, except He, have four pairs of dots in their electron dot diagrams. Noble gases are chemically stable. Lesson 1 - VS

D) Where on the periodic table are nonmetals located? A. the left side B. the right side C. the middle D. all of the above Lesson 1 – LR1

E) Which term refers to areas of space in which electrons move around the nucleus? A. electron dot diagram B. periodic table C. neutron D. energy levels Lesson 1 – LR2

F) All of the elements in group 18 are called what? A. metalloids B. valence electrons C. noble gases D. metals Lesson 1 – LR3

Lesson 2 Reading Guide - KC Compounds, Chemical Formulas, and Covalent Bonds How do elements differ from the compounds they form? What are some common properties of a covalent compound? Why is water a polar compound? Lesson 2 Reading Guide - KC

Chemical bonds hold atoms together. From Elements to Compounds Compounds are chemical combinations of different types of atoms. Chemical bonds hold atoms together. Lesson 2-1 This Photo by Unknown Author is licensed under CC BY-SA

From Elements to Compounds (cont.) How is a compound different from the elements that make it up? Lesson 2-1

Covalent Bonds—Electron Sharing A covalent bond is a chemical bond formed when two atoms share one or more pairs of valence electrons. A compound formed from many covalent bonds is called a covalent compound. Lesson 2-2

Atoms with less than eight valence electrons become chemically stable by forming a chemical bond. Lesson 2-2

Covalent Bonds—Electron Sharing (cont.) A single covalent bond exists when two atoms share one pair of valence electrons. A double covalent bond exists when two atoms share two pairs of valence electrons A triple covalent bond exists when two atoms share three pairs of valence electrons. Lesson 2-2

The more valence electrons that two atoms share, the stronger the covalent bond is between the atoms. Lesson 2-2

Covalent Compounds When two or more atoms share valence electrons, they form a stable covalent compound. Covalent compounds usually have low melting points and low boiling points. They are usually gases or liquids at room temperature, but they can also be solids. Covalent compounds are poor conductors of thermal energy and electricity. Lesson 2-3

Lesson 2-3

Covalent Compounds (cont.) A molecule is a group of atoms held together by covalent bonding that acts as an independent unit. A molecule that has a partial positive end and a partial negative end because of unequal sharing of electrons is a polar molecule. Lesson 2-3

Atoms of a polar molecule share their valence electrons unequally. Lesson 2-4

Atoms of a nonpolar molecule share their valence electrons equally. Lesson 2-4

Covalent Compounds (cont.) Why is water a polar compound? Lesson 2-4

A chemical formula is a group of chemical symbols and numbers that represent the elements and the number of atoms of each element that make up a compound. A chemical formula describes the types of atoms in a compound or a molecule, but it does not explain the shape or appearance of the molecule. Lesson 2-3

Chemical formulas and molecular models provide information about molecules. Lesson 2-4

A chemical formula is one way to show the elements that make up a compound. Lesson 2 - VS

A covalent bond forms when atoms share valence electrons A covalent bond forms when atoms share valence electrons. The smallest particle of a covalent compound is a molecule. Lesson 2 - VS

Water is a polar molecule because the oxygen and hydrogen atoms unequally share electrons. Lesson 2 - VS

Which term refers to chemical combinations of different types of atoms? A. covalent bond B. chemical formula C. compound D. polar molecule Lesson 2 – LR1

When two atoms share one pair of valence electrons, which of the following exists? A. single covalent bond B. double covalent bond C. triple covalent bond D. none of these Lesson 2 – LR2

Which term refers to a molecule that has a partial positive end and a partial negative end because of unequal sharing of electrons? A. covalent bond B. polar molecule C. nonpolar molecule D. covalent compound Lesson 2 – LR3

Do you agree or disagree? 3. The atoms in a water molecule are more chemically stable than they would be as individual atoms. 4. Many substances dissolve easily in water because opposite ends of a water molecule have opposite charges. Lesson 2 - Now