Compounds and Bonds

Chapter 2 - Chemical Interaction Compounds and Bonds

Warm up: Define the following terms on the front of your compounds packet

COMPOUND: A substance made up of 2 or more different types of atoms bonded together

Chemical Formula: An expression that shows the number of and type of atom in a compound For example: C6H12O6 Types of elements: carbon, hydrogen and oxygen How many (number): 6 Carbon, 12 Hydrogen, 6 Oxygen

Subscript: A number written slightly below the and to the right of a chemical symbol that shows how many atoms of an element are in a compound. C6H12O6

Ionic bond: The electric attraction between a negative and a positive ion.

Covalent Bond: A pair of electrons shared by 2 atoms

Metallic Bond: A certain type of bond in which nuclei float in a sea of electrons

Today's Topic: How atoms are combined in a compound (bonded), determine the properties of the compounds

CHEMICAL BOND: The force holding 2 atoms together in a compound. 3 Major Types of Bonds: Metallic, Ionic, Covalent

Metallic Bonds: are caused by mobile (moving electrons), this gives metal atoms the freedom to move around, therefore metal bend

Ionic Bonds: are caused by the formation of ions, this bond allows salt to dissolve in water. When an ionic compound dissolves it separates into ions which conduct electricity. Whereas covalent bonds do not!

Covalent bonds: the atoms share electrons, sometimes one atom pulls to hard on the electrons giving the atom 2 oppositely charged ends. What do you know about opposites: THEY: __________________ ATTRACT Therefore these molecules will :stick to each other...this is called COHESION

COHESION: The attraction between 2 like Molecules!!!! Example: H2O

SURFACE TENSION ON A PENNY!

The water forms a bubble on the penny! This is due to surface tension caused by the attraction of the water molecules to each other. Instead of falling off the penny the water molecules hold each other in place creating a dome on the penny.

Capillary Action: Take a look at your celery, write down what you notice on the back of your lab. Capillary Action - the tendency of water to travel up a small narrow tube. This is also caused by the polarcovalent bonds in the water molecule

COHESION: water to water, molecules of the same substance attract. ADHESION: water to tube (xylem), molecules of different substances attract. Water flow up the xylem of plant due to the uneq

Cohesion (attraction) between the water molecules, and the Adhesion between the xylem and the water cause the water to move up the small tubes called xylem in the celery

Warm up: Define the following terms on the front of your compounds packet

MOLECULE A group of atoms that are held together by covalent bonds so that they move as a unit.

Polar Covalent Bond The unequal sharing of electrons between 2 atoms that gives rise to negative and positive regions of electric charge.

Non-Polar Covalent Bond The unequal sharing of electrons between 2 atoms

COMPOUND: A substance made up of 2 or more different types of atoms bonded together

CHEMICAL BOND: The force holding 2 atoms together in a compound. 3 Major Types of Bonds: Metallic, Ionic, Covalent

Compounds are 2 or more elements held together with a CHEMICAL BOND. • Properties of compounds depend on the elements that make them up and how those element are BONDED to each other. These properties are usually very DIFFERENT from the individual elements that make them up.

The same elements can form different different compounds with different properties: Example: H2O = water - safe to drink, does not kill bacteria H2O2 = hydrogen peroxide, makes you vomit, used to kill bacteria

Bonding Occurs due to the fact that every atom wants to acquire: 8 VALENCE ELECTRONS - VALENCE ELECTRONS: are the electrons in the outermost energy level of an atom (farthest away from the nucleus) - A Full valence shell requires 8 valence electrons. With the exception of Helium because helium 1st energy level is filled with only 2.

Draw a Bohr model diagram of helium-4 and label the valence electrons 4 P: M: E: N: # valence e-: Questions: does helium-4 have a full valence shell: ____________ He

Draw a Bohr model diagram of carbon-14 and label the valence electrons 14 P: M: E: N: # valence e-: Questions: does carbon-14 have a full valence shell: ____________ C

Draw a Bohr model diagram of Neon-20 and label the valence electrons 20 P: M: E: N: # valence e-: Questions: does Neon-20 have a full valence shell: ____________ Ne

3 Main Types of Bond: Metallic Bonds Covalent Bonds Ionic Bonds

METALLIC BOND: Bond between 2 METALS. • Considered to be a "sea of electrons" with positive and "islands" (nuclei)

V Black = electrons, V=Valence electrons, Blue = proton, Red = neutrons

2. COVALENT BOND: electrons are SHARED. • A bond between 2 NON-METALS

2 Types of Covalent Bond POLAR and NON-POLAR • NON-POLAR BONDS: an equal sharing of electrons, between atoms. Occurs between 2 atoms of the same element.

2. Polar Bonds: an UNEQUAL sharing of electrons between atoms. Occurs between 2 atoms from different elements. Bond between two different elements of atoms (element) - Creating a slight negatively charges side and a slight positively charged side.

The polarity causes CAPILLARY ACTION, ADHESION, COHESION, SURFACE TENSION, and allows plants move water up their stems for photosynthesis

Cohesion Attraction between 2 LIKE molecules (2 of the same types of molecules sticking together)

Adhesion Attraction between 2 UNLIKE molecules (2 different type molecules sticking together)

Surface Tension Cohesive forces in water that cause it to bead and form a thin elastic film layer

Capillary Action - the tendency of water to move up a narrow tube. (Caused by the adhesion (attraction) of the water molecule to the side of the tube, and cohesion (attraction) between the water molecules. The water sticks together and pulls a trail of water up the tube (attraction)).

Use your notes to define the following terms on the vocab list on the front of your packet: Cohesion Adhesion Surface Tension Capillary Action

Compounds and Bonds