elements and the periodic table introduction to atoms organizing the elements metals nonmetals and...

Elements and the Periodic Table

Introduction to Atoms

Organizing the Elements

Metals

Nonmetals and Metalloids

Elements From Stardust

Table of Contents


Structure of an Atom

A carbon atom consists of protons and neutrons in a nucleus that is surrounded by electrons.

- Introduction to Atoms


Models of Atoms


For over two centuries, scientists have created models of atoms in an effort to understand why matter behaves as it does. As scientists have learned more, the model of the atom has changed.


4

Rutherford’s experiment circa 1909(alpha scattering experiment)

1/8000 alpha particle were deflected

Like a Toyota hitting a Mack truck!!Rutherford had discovered the

nucleus


5

Alpha particles scattered from the gold foil


6

Properties of Subatomic Particles


Isotopes

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



Structure of an Atom

Q. What particles are in the center of the atom?

A. Protons and neutrons

Q. What particles move around the outside of the nucleus?

A. Electrons



End of Section:Introduction to

Atoms


10

Periodic Table DevelopmentSeveral Early Schemes to Organize Elements

Mendeleev & Meyer (1869)

Organized elements by atomic mass

Noticed a pattern of properties when he arranged elements in order of increasing atomic

mass

Moseley (1913)

Post-doctoral student working in Rutherford’s lab

Organized elements by atomic number at age 26

Tragically killed in WW I


Organization of the Periodic Table

The 18 columns of the periodic table reflect a repeating pattern of properties that generally occur across a period.

- Organizing the Elements


13

Complete Periodic Table


Finding Data on Elements

Each square of the periodic table includes an element’s atomic number, chemical symbol, name, and atomic mass.



15

Fusion


Formation of the elements• Fusion of Hydrogen isotopes in stars releases energy• Heavier elements are forms due to fusion and the and very large gravitational

forces in the center of stars•Heavier elements like carbon, nitrogen, oxygen are produced in large stars

• Elements heavier than oxygen are produced in supernova at temperatures of a billion degrees!


What pattern of elements did Mendeleev discover?

Patterns appeared when the elements were arranged in order of increasing atomic mass.

What data about elements is found in the periodic table?

Atomic number, chemical symbols and names, and average atomic mass

How are elements organized in the periodic table?

Elements are organized in periods and groups based on their properties.

Question Answers



End of Section:Organizing the

Elements


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



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.

- 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.

- Metals



Melting points decrease from lithium to francium.

Reading Graphs:

As you look at Group 1 from lithium to francium, describe how the melting points of the alkali metals change.

- Metals



New element 119 should have a melting point of approximately 25ºC.

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.

- Metals



None of the alkali metals are liquids at room temperature. Cesium and francium might melt if you could hold them in your hand.

Interpreting Data:

Room temperature is usually about 22ºC. Human body temperature is 27ºC. Which of the alkali metals are liquids at room temperature? Which might melt if you could hold them in your hand?

- Metals



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

- Metals



Only some of the elements in Groups 13 through 15 of the periodic table are metals. These metals are not nearly as reactive as those on the left side of the table.

- Metals



Lanthanides are soft, malleable, shiny metals with high conductivity.

- Metals



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.

- Metals


What You Know

What You Learned

Using Prior KnowledgeBefore you read, write what you know about metals in a graphic organizer like the one below. As you read, write what you learn.

1. Metals are shiny.2. Some metals are magnetic.

1. Ductile metals can be pulled into a wire.2. Alkali metals react by losing one electron.

- Metals


End of Section:Metals


Properties of Nonmetals

When nonmetals react with metals, one or more electrons move from the metal atoms to the nonmetal atoms.

- Nonmetals and Metalloids


Families of Nonmetals

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




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




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




The Group 17 elements are the most reactive nonmetals. Atoms of these elements easily form compounds by sharing or gaining one electron when reacting with atoms of other elements.




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




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



The Metalloids

The metalloids have some characteristics of both metals and nonmetals. The most useful property of the metalloids is their varying ability to conduct electricity.



Using Prior KnowledgeBefore you read, write what you know about nonmetals in a graphic organizer like the one below. As you read, write what you learn.

What You Know

What You Learned

1. Nonmetals are not shiny.2. Nonmetals are not magnetic.

1. Nonmetals are dull and brittle.2. Metalloids have characteristics of metals and

nonmetals.



End of Section:Nonmetals and

Metalloids


How Elements Form in Stars

Nuclear fusion, which occurs in stars on a huge scale, combines smaller nuclei into larger nuclei, creating heavier elements.

- Elements From Stardust


SequencingAs you read, make a flowchart like the one below that shows how elements are formed in stars. Write the steps in separate boxes in the flowchart in the order in which they occur. Hydrogen nuclei fuse, forming helium.

Helium nuclei fuse, forming beryllium.

Fusion continues in smaller stars, forming elements up to oxygen.

Fusion in larger stars produces heavier elements up to iron.

The heaviest elements form during supernova explosions of the most massive stars.



Links on Nuclear Fusion

Click the SciLinks button for links on nuclear fusion.



End of Section:Elements From

Stardust


Graphic Organizer

Elements

Atomicnumber

Periods Families

Groups

Periodic table

Rows Columns

Patterns of properties

organizes

called called

or

is made up of

and shows

in order of increasing


End of Section:Graphic Organizer

elements and the periodic table introduction to atoms organizing the elements metals nonmetals and...

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pattern of elements

metalloids elements

periodic table introduction

periodic table structure

periodic table development

periodic table formation

complete periodic table

elements atomic number