Ch 2.3 Elements & Compounds

Objectives

• Explain the difference between an element and a compound.

• Identify the chemical symbols of elements, and name elements.

• Do you see Chemistry in this picture? Most people say no, they don’t. “Chemistry” can’t be “seen.”

• Therefore, Scientists represent atoms by using different colored circles, called a model.

• Models are tools that scientists use.

• Matter is composed of tiny particles called atoms.

• Not all atoms are alike, all matter is composed of about 100 different types of atoms.

• We call these 100 types of atoms the elements of the universe.

• Substances which cannot be broken down into simpler substances by chemical reactions are called elements.

Elements and Element Symbols

• Each element is unique. Elements have their own physical and chemical characteristics.

• Below is an example of each element in “model format.” An element in model form is a single, colored circle.

• A model is a visual of experimental data. Chemists use models to represent matter, such as elements

• Elements are organized in a table called the periodic table of the elements

• This will be the most important tool that you will use in this class

• What is the most important tool you will use in Chemistry? Listen to this engineer…

• An element is identified by its symbol; this consists of one or two letters, usually derived from its name:

C = Carbon

Co = Cobalt

• Sometimes the element symbol does not match the element name. This occurs because the Latin name is sometimes used, i.e.

Cu = Copper (Cuprum)

• If you look at the table below, other languages (other than Latin) are used for element symbols.

• Each element is different from other elements because it has a different number of protons.

• As a result each element has unique physical & chemical properties.

Element Symbol Reivew

• Question#1: What is the symbol of the element phosphorus?

A) P C) K

B) Po D) Kr

• Question#1 Answer: What is the symbol of the element phosphorus?

A) P C) K

B) Po D) Kr

• Question#2: What is the symbol of the element potassium?

A) P C) K

B) Po D) Kr

• Question#2 Answer: What is the symbol of the element potassium?

A) P C) K

B) Po D) Kr

• Question#3: What is the symbol of the element Krypton?

A) P C) K

B) Po D) Kr

• Question#3 Answer: What is the symbol of the element Krypton?

A) P C) K

B) Po D) Kr

• Question#4: What is the symbol of the element Polonium?

A) P C) K

B) Po D) Kr

• Question#4 Answer: What is the symbol of the element Polonium?

A) P C) K

B) Po D) Kr

The Atomic Number

• Elements are organized in the periodic table by the “Blue Number” called the atomic number.

• The atomic number is the number of protons in the element.

Atomic Number Review

• Question#1: What is the atomic number of the element phosphorus?

A) P C) K

B) Po D) Kr

• Question#1 Answer: What is the atomic number of the element phosphorus?

A) P = 15 C) K

B) Po D) Kr

• Question#2: What is the atomic number of the element potassium?

A) P C) K

B) Po D) Kr

• Question#2 Answer: What is the atomic number of the element potassium?

A) P C) K = 19

B) Po D) Kr

• Question#3: What is the atomic number of the element Krypton?

A) P C) K

B) Po D) Kr

• Question#3 Answer: What is the atomic number of the element Krypton?

A) P C) K

B) Po D) Kr = 36

• Question#4: What is the atomic number of the element Polonium?

A) P C) K

B) Po D) Kr

• Question#4 Answer: What is the atomic number of the element Polonium?

A) P C) K

B) Po = 84 D) Kr

Ch 2.1 Elements Are Pure Substances

Objectives:

• Categorize a sample of matter as a substance or a mixture.

• Pure substances have fixed properties: – Fe is a metal and

magnetic

– S is a nonmetal and not magnetic

• Elements are pure substances.

Elements At The Atomic Level

• Pure substances have a fixed constant composition.

• Elements are all the same,

thus a pure substance.

http://www.privatehand.com/flash/elements.html The Element Song

• Practice Problems To Complete:

–Protons (p+), Elements, Compounds

–Element Word Search