CHAPTER 4: FOOD CHEMISTRYFood Science I

DeCrescentis

PRE-TEST

1. Is food Matter?2. In order to be matter what 2 characteristics does it need?3. What is an atom?4. What are the parts of an atom?5. What is an element?

6. Name an element most commonly found in food?7. Give an example of a physical change in food?8. Give an example of a chemical change in food?9. What are the phases or states of matter?10. What is a compound?

WHY IS CHEMISTRY IMPORTANT?

Processing food Packaging food Preserving food Adjusting for recipes –altitude

WHAT IS CHEMISTRY?

Chemistry is the study of the make-up, structure, and properties of substances and the changes that occur to them.

Matter is anything that occupies space and has mass.

THE BASIC NATURE OF MATTER

Everything you encounter is made up of atoms.

An atom is the smallest unit of a substance.

We cannot see atoms, even with powerful microscopes.

ATOMS Atoms are made up of subatomic

molecules. The nucleus is in the center of

the atom and is made up of neutrons and protons. A proton has a positive charge and a neutron has a neutral charge.

Electrons are an even smaller unit and have a negative charge.

THE CLASSIFICATION OF MATTER Pure Substances:

Can be grouped by elements and compounds All basic units are the same. Example: Baking Soda

Mixtures: Put together, but not chemically combined Example: Milk contains calcium and salt

There are 2 types of mixtures:

Heterogeneous and Homogeneous.

MIXTURES Heterogeneous mixture:

Non-uniform Examples: salad, vegetable soup. (You can see all

ingredients) If you puree soup or salad in a blender it would become

homogeneous.

Homogeneous mixture: Uniform distribution of particles throughout You cannot tell one part of the mixture from another Examples: alfredo sauce, milk, mayonnaise

MIXTURES CONT.

Is hot chocolate a homogenous mixture or a heterogeneous mixture?

Solution: One material is dissolved into another. The material dissolved is called the solute.

PHYSICAL AND CHEMICAL CHANGES Physical Change: Change the temperature,

shape, size, or physical state of an object without changing the chemical makeup of the substance. Example: freezing water or melting ice

Chemical Change: Color, odor, or flavor change. Example: baking bread or fermenting grapes.

ELEMENTS

There are 90 naturally occurring elements

An element is a substance that only contains one type of atom

The number of protons in the nucleus determines which element the atom is.

THE PERIODIC TABLE The atomic number is

how many protons are in the nucleus

The atomic mass is the number of protons plus neutrons in the atom

Electrons are so small the mass is insignificant.

METALS AND NONMETALS

The table is categorized into metals and nonmetals. Metals are usually shiny at rom temperature, where as non-metals are not.

Most nonmetals are gases at room temperature.

COMPOUNDS AND CHEMICAL FORMULAS

Compounds= Substances in which two or more elements have chemically combined.

The basic unit of a compound= Molecule. Chemical Formula= A combination of

symbols and elements to make up a compound. Example: H2O is the chemical formula

for water.

BONDS

A chemical bond is a force that hold two atoms together.

There are two types of chemical bond: Ionic and Covalent. Ionic= electrons are transferred from

one atom to another Covalent= atoms share one or more

pairs of electrons