Table of Contents Chapter Preview 4.1 Introduction to Atoms 4.2 Organizing the Elements 4.3 Metals 4.4 Nonmetals, Inert Gases, and Semimetals 4.5 Radioactive Elements Chapter Preview 4.1 Introduction to Atoms 4.2 Organizing the Elements 4.3 Metals 4.4 Nonmetals, Inert Gases, and Semimetals 4.5 Radioactive Elements

Chapter Preview Questions 1. Groups of two or more atoms held together by chemical bonds are a. elements. b. molecules. c. particles. d. electrons.

Chapter Preview Questions 1. Groups of two or more atoms held together by chemical bonds are a. elements. b. molecules. c. particles. d. electrons.

Chapter Preview Questions 2. When elements are chemically combined in a set ratio, they form a. molecules. b. matter. c. elements. d. compounds.

Chapter Preview Questions 2. When elements are chemically combined in a set ratio, they form a. molecules. b. matter. c. elements. d. compounds.

Chapter Preview Questions 3. Which of the following is an example of an element? a. copper b. rust c. concrete d. water

Chapter Preview Questions 3. Which of the following is an example of an element? a. copper b. rust c. concrete d. water

Chapter Preview Questions 4. Two compounds with different properties are a. C and O. b. H and O. c. CO and CO2. d. Cl and Ar.

Chapter Preview Questions 4. Two compounds with different properties are a. C and O. b. H and O. c. CO and CO2. d. Cl and Ar.

How is the periodic table organized? Imagine you have a piece of aluminum foil, and you cut it in half. If each of these pieces is cut in half a second, third, and fourth time, the pieces become smaller but are still aluminum. How small must a piece be so that at the next cut it will no longer be aluminum?

Greek Word Origins alpha First letter of the Greek alphabet Greek Origin Meaning Key Words First letter of the Greek alphabet alpha Alpha particle

Greek Word Origins atomos Cannot be cut; indivisible Greek Origin Meaning Key Words atomos Cannot be cut; indivisible Atom, atomic number, atomic mass

Greek Word Origins beta Second letter of the Greek alphabet Greek Origin Meaning Key Words beta Second letter of the Greek alphabet Beta particle

Greek Word Origins di Two, double Diatomic molecule Greek Origin Meaning Key Words di Two, double Diatomic molecule

Greek Word Origins gamma Third letter of the Greek alphabet Greek Origin Meaning Key Words Third letter of the Greek alphabet gamma Gamma radiation

Greek Word Origins hals Salt, relating to salt Halogen Greek Origin Meaning Key Words hals Salt, relating to salt Halogen

Apply It! Review the Greek origins and meanings in the chart. What is the meaning of the prefix di- in diatomic? Predict the meaning of diatomic molecule. Revise your definition as needed. Sample: Since diatomos means “two atoms,” di- probably means “two.”

End of Chapter Preview

Section 1: Introduction to Atoms How did atomic theory develop and change? What is the modern model of the atom?

Atomic Theory and Models Dalton thought that atoms were like smooth, hard balls that could not be broken into smaller pieces.

Atomic Theory and Models Thomson suggested that atoms had negatively charged electrons embedded in a positive sphere.

Rutherford’s Gold Foil Experiment Rutherford was surprised that a few particles were deflected strongly. This led him to propose an atomic model with a positively charged nucleus.

Later Atomic Models Through the first part of the twentieth century, atomic models continued to change.

Modern Model of an Atom This model of a carbon atom consists of positively charged protons and neutral neutrons in a nucleus that is surrounded by a cloud of negatively charged electrons.

Particles in an Atom An atom is composed of positively charged protons, neutral neutrons, and negatively charged electrons. Protons and neutrons are about equal in mass. An electron has about 1/2,000 the mass of a proton or neutron.

Isotopes Atoms of all isotopes of carbon contain six protons and six electrons, but they differ in their number of neutrons. Carbon-12 is the most common isotope.

More on Atomic Structure Click the PHSchool.com button for an activity about atomic structure.

End of Section: Introduction to Atoms

Section 2: Organizing the Elements How did Mendeleev discover the pattern that led to the periodic table? How are the elements organized in the modern periodictable?

The Periodic Table Elements are organized into rows and columns based on their atomic number.

The Periodic Table Elements are organized into rows and columns based on their atomic number.

The Periodic Table Elements are organized into rows and columns based on their atomic number.

Periodic Table Activity Click the Active Art button to open a browser window and access Active Art about the periodic table.

Finding Data on Elements Each square in the periodic table lists four pieces of information: an element’s atomic number, chemical symbol, name, and atomic mass.

End of Section: Organizing the Elements

Section 3: Metals What are the physical properties of metals? How does the reactivity of metals change across the periodic table? How are synthetic elements produced?

Metals in the Periodic Table The metals in Group 1, from lithium to francium, are called the alkali metals. Alkali metals react with atoms of other elements by losing one electron.

Metals in the Periodic Table Group 2 of the periodic table contains the alkaline earth metals. These elements are not as reactive as the metals in Group 1, but they are more reactive than most other metals.

Melting Points in a Group of Elements The properties of elements within a single group in the periodic table often vary in a certain pattern. The following graph shows the melting points of Group 1 elements (alkali metals) from lithium to francium.

Melting Points in a Group of Elements Reading Graphs: As you look at Group 1 from lithium to francium, describe how the melting points of the alkali metals change. Melting points decrease from lithium to francium.

Melting Points in a Group of Elements Predicting: If element number 119 were synthesized, it would fall below francium in Group 1 of the periodic table. Predict the approximate melting point of new element 119. New element 119 should have a melting point of approximately 25ºC or lower.

Melting Points in a Group of Elements Interpreting Data: Which of the alkali metals are liquids at 35ºC? Cesium, francium

Metals in the Periodic Table The transition metals are less reactive than the metals in Groups 1 and 2.

Metals in the Periodic Table Only some of the elements in Groups 13 through 15 of the periodic table are metals.

Metals in the Periodic Table Lanthanides are usually found together in nature, always combined with other elements.

Metals in the Periodic Table The elements below the lanthanides are called actinides. Many of these elements are so unstable that they last for only a fraction of a second after they are made.

Click the SciLinks button for links on metals.

End of Section: Metals

Section 4: Nonmetals, Inert Gases, and Semimetals What are the properties of nonmetals and inert gases? How are semimetals useful?

Properties of Nonmetals When nonmetals and metals react, electrons move from the metal atoms to the nonmetal atoms.

Families of Nonmetals Each element in the carbon family has atoms that can gain, lose, or share four electrons when reacting with other elements.

Families of Nonmetals Group 15, the nitrogen family, contains two nonmetals: nitrogen and phosphorus. These non-metals usually gain or share three electrons when reacting with other elements.

Families of Nonmetals Group 16, the oxygen family, contains three nonmetals: oxygen, sulfur, and selenium. These elements usually gain or share two electrons when reacting with other elements.

Families of Nonmetals The Group 17 elements, the halogens, are very reactive. Atoms of these elements easily form compounds by sharing or gaining one electron when reacting with atoms of other elements.

Families of Nonmetals The elements in Group 18 are the inert gases. They do not ordinarily form compounds because atoms of inert gases do not usually gain, lose, or share electrons.

Families of Nonmetals Because the chemical properties of hydrogen differ very much from those of the other elements, it really cannot be grouped into a family.

Semimetals The most useful property of the semimetals is their varying ability to conduct electric current.

Click the SciLinks button for links on nonmetals.

End of Section: Nonmetals, Inert Gases, and Semimetals

Section 5: Radioactive Elements How was radioactivity discovered? What types of particles and energy can radioactive decay produce? In what ways are radioactive isotopes useful?

Types of Radioactive Decay During alpha decay, a nucleus loses an alpha particle, which consists of two protons and two neutrons.

Types of Radioactive Decay During beta decay, a neutron inside an unstable nucleus changes into a negatively charged beta particle and a proton.

Types of Radioactive Decay Gamma radiation has no charge and does not cause a change in either the atomic mass or the atomic number.

Types of Radioactive Decay The three types of nuclear radiation were named based on how easily each one could be blocked. Alpha, beta, and gamma are the first three letters of the Greek alphabet.

Using Radioactive Isotopes Tracers are radioactive isotopes that can be followed through the steps of a chemical reaction or industrial process.

Radioactive Tracers Activity Click the Active Art button to open a browser window and access Active Art about radioactive tracers.

Click the Video button to watch a movie about radiation.

End of Section: Radioactive Elements

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