Chapter 2: Matter

Section 1: Atoms

A. Building Blocks of Matter

1. Matter: anything that has mass and takes up space

a. Taking up space = volume

2. Matter comes in 4 states:

a. Solids: matter with definite shape

b. Liquids: matter that has the ability to flow

c. Gas: vaporized form of matter

d. Plasma: High Energy state of matter

3. All matter is made up of atoms

B. Atoms

1. The atom is the smallest particle of any element that has the properties of the element.

2. The structures of different types of atoms and how they join together determine all the properties of matter that you can observe. (See the next slide)

a. Atoms cannot be seen.

b. Only indirectly observed.

c. Make up anything that has mass and volume.

C. Elements

1. Elements are substances that are made of only ONE type of atom and cannot be broken down into simpler substances by normal or chemical means.

2. Elements combine to make a variety of items.

a. Most minerals usually are combinations of atoms

b. Some minerals are made up of only one element.

c. Why is electrical wire made up of copper?

d. See Table 1

3. Elements are represented by symbols.

4. Some symbols come from the Latin Name

a. Fe = iron (From ferris)

b. NA= sodium (natrium)

c. Pb= Lead (from plumbum)

5. Some symbols come from the common name.

a. O= Oxygen

b. N= Nitrogen

c. Ne= Neon

6. Newest Elements are produced in labs.

a. Names given by creator.

b. Symbols are usually 3 letters.

7. Writing elements correctly

a. Some are 1 letter, others are 2 and 3 letters.

b. First letter is ALWAYS capitalized.

c. 2nd and 3rd letters are lower case.

d. This prevents confusion.

8. Examples:

a. CO= Carbon Monoxide (two capital letters means two elements combined to form compound)

b. Co= Cobalt (one capital letter means element)

9. Periodic Table of Elements

a. Created by Dimitri Mendeleev in 1869; Russian Chemist

b. Arranged all elements by their mass.

c. Noticed a repeating pattern.

d. Began a new row every time a new patter began.

e. Periodic means “to repeat”

f. The periodic table is arranged in rows according to atomic number and in columns by properties.

DO NOT COPY THIS SLIDE

D. Modeling Atoms

1. When something is too large or too small to observe directly, models can be used.

a. Give an example of a model

E. The History of the Atomic Model

1. 2300 years ago, the Greek philosopher Democritus proposed matter is composed of atoms.

2. 2000 years later John Dalton theorized that all atoms of an ELEMENT contain the same type of atom.

F. Protons and Neutrons

1. Protons: particles found inside the nucleus that have a positive charge.

2. Neutrons: particles found inside the nucleus that have no electric charge. (Neutral)

3. Protons and Neutrons have the same mass.

a. 1800 times heavier than an electron.

4. Protons are neutrons are made up of QUARKS.

G. Electrons

1. Particle with a negative charge.

2. Electrons have very little mass.

3. Found outside the nucleus.

4. 1913 Niels Bohr proposed an atom’s electrons travel in orbit-like paths around the nucleus in the electron cloud.

5. Electrons that are closer to the nucleus have lower energy.

6. Electrons that are farther from the nucleus have higher energy.

H. Current Atomic Model

1. Electron Shell Energy Levels

a. Closest to nucleus: 2 electrons

b. Second Shell holds up to 8 electrons

c. Third Shell holds up to 18 electrons

d. Fourth Shell holds up to 32 electrons

e. All shells farther out can hold up to 64 electrons.

2. Electrons always try to arrange in pairs.

3. Electrons do not travel in orbit-like paths; instead surround the nucleus in a cloud.

a. Can be anywhere in the cloud; but are near nucleus most of the time.

b. Energy levels are still accurate.

I. Counting Atomic Particles

1. Atomic Number= number of protons in the nucleus.

a. This number can be found above the element symbol on the periodic table. (Back of Book)

b. Bottom left corner of the example in your notes.

2. All atoms of the same element MUST have the same number of protons!!!!!

a. All hydrogen atoms have 1 proton!!

J. How many electrons?

1. Atomic number= # of protons= # of electrons

2. Atoms tend to be neutral (Charge of zero)

K. How many Neutrons?

1. Atoms can have a different # of neutrons.

2. # of neutrons are not found on periodic table.

3. Mass Number= Neutrons + Protons

4. How to find # of neutrons

a. Mass # - Atomic # = # of neutrons

b. Why does this work?????

L. What are Isotopes?

1. Isotopes are atoms of the same element with a different number of neutrons.

a. Example: Hydrogen has 1 proton, but can have 0, 1, or 2 neutrons; therefore has 3 possibilities.

Carbon Isotopes

Isotopes in Medicine