ATOMS and Molecules

http://www.youtube.com/watch?v=Xy2Gyz3w5d8

ESSENTIAL QUESTION How do we distinguish between atoms and molecules?

Definition of ATOM is the smallest particle into which an element can be divided and still be the same substance

What is an Element? Definition of Element: A substance that cannot be broken down into other substances by chemical or physical means.

WHAT’S THE BIG IDEA?? Atoms are composed of small particles that determine the properties of the atom. There are three types of subatomic particles: Neutron – neutral charge; holds the protons in the center of the atom (nucleus); largest Proton -- positively charged particles; determines the identity of the element; Electron – negatively charged particles; smallest; rapidly move around the nucleus

WHAT IS AN ATOM MADE OF?

ATOMS The atom is held together by nuclear forces -- the positive protons and the negative electron attract each other.

ATOMIC MODELS (Bohr Model) 1. Nucleus -- protons and neutrons are in the center of the atom called the nucleus; 2. Electron Shells -- electrons travel outside the nucleus in "special orbits"; each orbit can only hold a specific number of electrons.

ATOMIC MODELS (Bohr Model) FOR EXAMPLE: Orbit #1 (closest to the nucleus) can hold only two (2) electrons. Orbit #2 can hold up to eight (8) electrons. Orbit #3 can hold up to eight (8) electrons.

What’s missing? Draw an arrow to it and Label Electrons Electron Shell + Protons Nucleus

ATOMIC MODELS (Modern Atomic Model) 1. Nucleus - protons and neutrons are in the center. 2. Electron Shells -- a region around the nucleus of an atom where electrons are likely to be found.

Molecules are very small objects that are made up of connected atoms What are Molecules? Molecules are very small objects that are made up of connected atoms

What Do Molecules Look Like? Molecules can take on all kinds of different shapes and sizes Let’s look at a few!

Water H H O H2O

Air Nitrogen N Oxygen O

Sugar C6H1206

Salt (Sodium Chloride) NaCl

It depends on whether they are in a solid, liquid, or gas Do Molecules Move? Yes, they do! How do they move? It depends on whether they are in a solid, liquid, or gas

IDENTIFYING SUBSTANCES ATOM – smallest unit of an element that maintains the properties of that element. EX: O MOLECULES – any two or more joined atoms that are the same or different COMPOUNDS – two or more different atoms that are joined EX: NaCl

Copy the chart and put a under the appropriate column(s). SUBSTANCE MOLECULE COMPOUND HCl

Molecule Activity

Molecule Activity 1. Water 2. Carbon Dioxide

Molecule Activity 3. Ammonia 4. Methane