Unit 1 Chemistry Basics

Transcription

1 Unit 1 Chemistry Basics Estimated Time: 1 hour Terminal Objective: At the completion of this unit, the students will identify basic chemistry concepts. Enabling Objectives: The students will: 1. Define Chemistry. 2. Describe the three different states of matter. 3. Describe the three basic components of an atom and the location of each within an atom. 4. Describe the difference between a pure substance and a compound. 5. Identify the first ten elements in order of increasing atomic number on the periodic table. 6. Describe two types of bonding whereby two or more elements can combine chemically to form a compound. Chemistry Defined What is Chemistry? The science of chemistry is the study of composition, structure, and properties of matter as well as the study of the reactions by which one form of matter is produced from or converted into other forms. These reactions may produce heat, pressure, explosions, and toxic by-products. Chemical reactions may be exothermic (heat-releasing) or endothermic (heat absorbing). States of Matter Matter All material is made up of the basic building blocks that combine to form matter. There are three basic states of matter: solids, liquids, and gases. For the purposes of this introduction to chemistry, we will consider the three basic states of matter: solids, liquids, and gases. Solids Solids have specific mass, occupy a specific volume, and have a specific shape. Molecules, atoms, or ions in solid states pack very close together. 1

2 Liquids Liquids have specific mass, occupy a specific volume, but have no specific shape. Liquids will conform to the shape of their container. Generally, liquids cannot be compressed. Liquids are generally in this state of matter due to pressure. Gases Gases have specific mass, but have no specific volume or shape. Atomic or molecular distance varies depending on its pressure. Pressure will compress all gases. Gases may simply compress, or with enough pressure, they may liquefy. Matter in this state is dependent upon pressure and temperature. Two important values that responders considered are: Critical Temperature Critical Pressure See the definitions of these two important points in the glossary! Components of Matter Atoms are the basic components of matter Atoms have three basic parts that are defined as sub-atomic particles. They are: Protons: Protons are found in the nucleus of the atom and have a positive charge (the charge is assigned a value of +1). Neutrons: Neutrons are also found in the nucleus of the atom and for the purposes of this course, will have a neutral charge (the charge is assigned a value of 0). Electrons: Electrons are found in a cloud or orbiting the atom and have a negative charge (the charge is assigned a value of -1). 2

3 Knowledge review Choose the correct response to the question below. 1. How many states of matter are discussed in this course? a Two states of matter b Three states of matter c Four states of matter The correct answer is three states of matter. Rationale: It is important for responders to use the state of matter when determining the potential for a material to spread. Because of this, course participants are expected to understand the concept of states of matter and be able to identify and define the three states of matter. 2. Materials that have specific mass, occupy a specific volume, and have a specific shape are best described to be in which state of matter? a Solids b Liquids c Gas d Plasma The correct answer is solids. Rationale: To determine the potential hazards of a specific material, a responder must identify the physical state of matter that the material is in. To do so requires that the course participants understand the concepts of states of matter and be able to identify and define the three states of matter. Solid materials are defined as having specific mass, occupy a specific volume, and having a specific shape. 3. Materials that have specific mass, occupy a specific volume, but have no specific shape best describes what state of matter? a Solids b Liquids c Gas d Plasma The correct answer is liquids. Rationale: To determine the potential hazards of a specific material, a responder must identify the physical state of matter that the material is in. To do so requires that the course participants understand the concepts of states of matter and be able to identify and define the three states of matter. 3

4 Important information about atoms Atoms must be electrically neutral. Very simply, the overall electrical charge must be electrically neutral. This occurs because the total number of positive charges of the protons offset the total number of negative charges of the electrons. Therefore, for the charge of the atom to be neutral, atoms must have the same number of electrons and protons. Because the charge of a neutron is electrically neutral, the number of neutrons does not enter into the calculation of the atom s overall charge. Ions can be positively charged or negatively charged. If an atom has a different number of electrons and protons, it is no longer called an atom, but will be called an ion. Positively charged ions are called cations. Negatively charged ions are called anions. Matter Matter can be pure substances or compounds. Pure substances are made up of atom(s) of one element. Compounds are a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. They consist of a fixed ratio of atoms. A compound can only be created by a chemical reaction. A chemical bond is an attraction between atoms that allows the formation of chemical substances (compounds) that contain two or more atoms. There are several types of bonding that can occur. For the purpose of this course, we will focus on two specific types of bonding, ionic and covalent. Ionic bonding occurs when two ions having opposite charges attract each other. Covalent bonding occurs between two or more anions. Periodic Table The Periodic Table arranges atoms The Periodic Table of Elements arranges atoms in order of increasing atomic number. The atomic number is the number of protons that the atom has in the nucleus. Each atom has a name and is represented on the periodic table by a one or two letter symbol. The first letter is always capitalized. If there is a second letter, it is always lower case. 4

5 Element Names and Symbols Each atom has a name and symbol. Below are the first ten elements and symbols as they appear on the periodic table. You should be able to identify the element by name, atomic number, or symbol. Knowledge review Choose the correct response to the question below. 1. Atoms have three basic parts that are defined as sub-atomic particles. What are these subatomic particles called? a Photons, newtons, and quarks. b Protons, neutrons, and electrons. c Protons, sub-atoms, and quarks. d Phase, position, and rotation. The correct answer is Protons, Neutrons, and Electrons. Rationale: To understand the complex chemical reactions, course participants must understand the makeup of the atom, including the roles of Protons, Neutrons and Electrons, as well as the location and charges of each of the sub-atomic particles. Complete the statement below 2. Atoms must be a Positively charged. b Negatively charged. c Electrically neutral. The correct answer is electrically neutral. Rationale: To understand the complex chemical reactions, course participants must understand the makeup of the atom, including the roles of protons, neutrons, and electrons, as well as the location and 5

6 charges of each of the sub-atomic particles. Atoms must have the same number of protons and electrons and therefore must have an overall charge that is neutral. Charged atoms are called ions. Periodic Table In addition to arranging atoms on the periodic table by increasing atomic number, the periodic table also groups atoms into families. These families of atoms exhibit the same or similar properties. The first column or family on the left of the periodic table is called the Alkali Metals. The second column is called the Alkaline Earth Metals. The next to last column on the right of the periodic table is called the Halogen Family. The last column on the right of the periodic table is called the Noble Gas Family. Compounds Bonding two or more atoms together Two or more atoms can bond together and form a compound. The type of a compound that is formed depends on the types of bonds. The two major categories of bonds are called ionic and covalent. Ionic Bonds usually occur between a metal and a non-metal. Covalent Bonds occur between two or more non-metals. Ionic Bonding In ionic bonding, the metal loses electrons to become a cation. The non-metal gains electrons to become an anion. The cations and anions are bound together because opposite charges attract. The compound that is formed is called a salt. Covalent Bonding In covalent bonding, the compound is formed between two or more non-metals. The non-metals hold their electrons very tightly and they are not able to take electrons away from other atoms. The result is that the atoms must share the electrons. A compound that is formed by sharing electrons is called a non-salt. Knowledge review Choose the correct response to the question below What are positively charged ions called? a Positrons b Negatrons c Cations d Anions The correct answer is cation. Rationale: To understand the concept of chemical bonding, each participant must understand the concept of ions and the charges that they carry. This is a critical step in understanding ionic and covalent bonding.

7 2. Ionic bonding occurs when a Two metals are mixed together. b Two salts are mixed together. c Two ions with opposite charges attract each other. d Two non-metals are attracted to each other. The correct answer is two ions with opposite charges attract each other. Rationale: To understand the concept of chemical bonding, each participant must understand the concept of ions and the charges that they carry. This is a critical step in understanding ionic bonding. 3. Covalent bonding occurs between a Two or more non-metals. b Two or more metals. c Metals and hydrogen. d Two cations. The correct answer is two or more non-metals. Rationale: Covalent bonding occurs when two or more non-metals share electrons. In covalent bonding, these non-metals hold electrons so tightly that other non-metals cannot transfer them. Therefore, they must be shared. Bonds between shared electrons are called Covalent Bonds. To understand the concept of chemical bonding, each participant must understand the concept of nonmetal elements and how they bond together. This is a critical step in understanding covalent bonding. Summary In this unit, you have learned: That chemistry is the study of matter, energy, and the interactions that take place in matter. That all atoms are made up of sub-atomic particles called protons, electrons, and neutrons. Protons carry a charge of +1 and electrons have a charge of -1. Neutrons have a neutral charge. Atoms are named and arranged on the periodic table in the order of increasing number of protons. The periodic table has important information that is a reference source for responders. How atoms form compounds through two types of bonding-- ionic and covalent. 7