2.4.W - Lesson Review: Matter & Periodic Table / Bonding/ Water & pH

Products

the ending material in an action

Chemical reaction

the making and breaking of chemical bonds to form or rearrange molecules

Reactants

the starting material in a reaction

What kind of bond is characterized by the sharing of electrons?

Covalent - Molecules formed by sharing electrons have covalent bonds.

Using your best grammar, discuss electronegativity and its relationship to polar and non-polar bonds. Write 3-5 sentences.

Electronegativity is the desire atoms have to share electrons. Elements that have similar electronegativity levels share electrons; this bond is called a nonpolar covalent bond. Elements that have different electronegativity levels don't share electrons equally; this bond is called a polar covalent bond.

Which particles are important for how an atom interacts with other atoms and for chemical reactions?

Electrons - Electrons are on the surface of the atom and are most important for chemical interactions.

In your own words, describe what pH is and why it is important. Write 2-4 sentences using your best grammar.

pH is the level of hydrogen ions there are in a solution that is water-based (aqueous). It is important when analyzing the composition of elements.

Which items are matter? Choose all that apply.

-Atoms -Water -Bricks

The polar nature of water and the hydrogen bonds it can form contribute to what properties of water? Choose all that apply.

-Cohesion and adhesion -The ability to moderate temperature -High surface tension -Expanding when frozen -Excellent solvent Water's ability to form hydrogen bonds contributes to many unique properties.

In what physical state does water exist in the natural environment? Choose all that apply.

-Gas -Solid -Liquid Water is one of the only common substances to exist in all three physical states in the natural environment.

Matter can be in what forms? Choose all that apply.

-Liquid -Solid -Gas

Which particles make up an atom? Check all that apply.

-Protons -Electrons -Neutrons

If a solution has a very low concentration of H+, it will have a pH in what range?

11-14 - A solution with a very low H+ concentration is a strong base, so it will have a pH between 11-14.

How many electrons in the outer shell of an atom are generally needed for stability?

8 - Generally, an atom is most stable when there are 8 electrons in its outer shell.

If a solution has a high concentration of H+, it is what?

Acidic - Solutions with high concentrations of H+ are acidic.

In your own words, define an atom, and describe how and what subatomic particles compose it. Use your best grammar to write 3-5 sentences on this topic.

Atoms make up everything. They have a nucleus at the center of them. There are protons and neutrons inside of it too. Around the nucleus are electrons. These electrons are what the atoms use to bond with other atoms and become more stable.

How are elements in the periodic table arranged?

By increasing atomic number - Arranging the elements by increasing atomic number also allows elements of similar properties to align in groups.

A neutral solution has what ratio of H+/OH-?

Equal - Neutral solutions have the same number of H+ and OH-.

Which of the following is not a function of a chemical reaction?

Freezing water - Chemical reactions form and break bonds to make and rearrange molecules; however, changes in states of matter are not chemical reactions.

In the periodic table, elements with similar properties are found in the same what?

Group - Different elements but with similar properties are arranged in columns, or groups.

Which of the following is not a molecule?

He - Single atoms are not molecules, but any combination of bonded atoms form molecules.

The number of which subatomic particle identifies an atom as a particular element?

Proton - The number of protons in the nucleus identifies which element an atom is.

The nucleus of an atom is made up of which subatomic particles?

Protons and neutrons - The nucleus is composed of protons and neutrons, and it makes up the vast majority of the mass of an atom.

The starting material in a chemical reaction is called what?

Reactants - The starting materials in a chemical reaction are called the reactants; the ending materials are called the products.

The pH of a solution describes what?

The concentration of H+ ions

In your own words, describe the octet rule and how this is related to the formation of chemical bonds. Use your best grammar to write 2-4 sentences.

The octet rule basically states that there needs to be eight electrons in the outer layer of an atom in order for it to be completely stable. The sharing of these electrons creates chemical bonds.

Why do atoms form bonds to achieve a full octet in the valence shell?

To gain stability - Atoms form bonds to achieve greater stability, and a full octet in the outer shell is most stable.

What is responsible for the ability of water to form hydrogen bonds?

Water's polar covalent bonds - Oxygen is a highly electronegative atom, so the electrons in water molecules spend more time around the oxygen than the hydrogens. This makes the bonds in water polar.

Endergonic

a chemical reaction that absorbs energy

Exergonic

a chemical reaction that releases energy

A molecule is when two or more atoms ______ together.

bond - Molecules are formed when atoms bond.

A _______ is a substance that keeps the pH of a solution relatively constant and is highly stable.

buffer - Buffers are very important for reactions that require a very specific pH range.