protons, neutrons, and electrons—how atoms differ1+lesson+11.pdfprotons, neutrons, and...

7th Grade Science

Isotopes and ions

UNIT 1 LESSON 11

Do Now

Name_____________________________________ Date:_____________________________________

26

Fe

Iron

55.845

Directions: Label the period table entry and fill in the missing blanks.

Atomic # = ______

Atomic Mass = _________

Mass # = _________

# of Protons = ________

# of Neutrons = ________

# of Electrons = ________

Understanding the Atom 33

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LESSON 2Content Practice B

Protons, Neutrons, and Electrons—How Atoms DifferDirections: Complete the chart with the correct terms from the word bank in the space provided. Some terms may be used more than once.

e- electron cloud around the nucleus n nucleus p

0 1/1,840 1- 1 1+

Properties of Protons, Neutrons, and Electrons

Electron Proton Neutron

Symbol 1. 5. 9.

Charge 2. 6. 10.

Location 3. 7. 11.

Relative Mass

4. 8. 12.

Directions: Answer each question on the lines provided.

13. What makes an atom of one element different from an atom of another element?

14. An element has 6 protons and 6 neutrons. What is its atomic number? What is its mass number?

15. What happens to a neutron atom if it gains or loses electrons?

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1/1,840 1

e-

nucleus

7th Grade Science

Isotopes

UNIT 1 LESSON 11

Notes

Name_____________________________________ Date:_____________________________________

Aim: SWBAT understand how a neutral atom changes when it’s numbers of protons, electrons, or neutrons change.

92 Understanding the Atom

Lesson 2

Skim Lesson 2 in your book. Read the headings and look at the photos and illustrations. Identify three things you want to learn more about as you read the lesson. Record your ideasin your Science Journal.

Protons, Neutrons, and Electrons—How Atoms Differ

Copyright © Glencoe/McGraw-Hill, a division of The M

cGraw-Hill Companies, Inc.

Distinguish parts of the atom.

Part Electron Proton Neutron

Symbol

Charge

Location

Relative Mass

Relate details about atomic number.

Atomic Number

determines equals , and also equals

in neutral atoms

Differentiate numbers of protons and neutrons in different isotopes of the same element.

Numbers of protons:

Numbers of neutrons:Isotopes of

the Same Element

Contrast the numbers of particles represented by an element’s mass number and atomic number.

Atomic Number Mass Number

The Parts of the Atom I found this on page .

Neutrons and IsotopesI found this on page .

Different Elements—Different Numbers of ProtonsI found this on page .

I found this on page .

1

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Different Elements – Different Numbers of Protons

What are the atomic numbers of carbon, nitrogen and oxygen? _________________________________ __________________________________________________________________________________________ Explain the difference between an oxygen atom and a carbon atom. _____________________________ __________________________________________________________________________________________


Lesson 2



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Symbol

Charge

Location

Relative Mass


Atomic Number


in neutral atoms


Numbers of protons:


the Same Element







1


Neutrons and Isotopes • Isotopes are atoms of the same element that have different

numbers of neutrons. Most elements have several isotopes.

How do the carbon isotopes differ? _____________________________________________________________________________ _____________________________________________________________________________

Atomic Number vs. Mass Number


Lesson 2



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Symbol

Charge

Location

Relative Mass


Atomic Number


in neutral atoms


Numbers of protons:


the Same Element







1


Average Atomic Mass

Define average atomic mass. _________________________________________________________ ________________________________________________________ ________________________________________________________ ________________________________________________________

How is the average atomic mass calculated? The abundance of each isotope is changed to decimal form. The mass of each isotope is multiplied by it’s corresponding decimal percentage. All the values are added together to determine the average atomic mass

0.989 x 12 = 11.868 0.0101 x 13= + 0.143 12.011

Independent Practice

Understanding the Atom 29

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Lesson Outline LESSON 2

Protons, Neutrons, and Electrons—How Atoms DifferA. The Parts of the Atom

1. Protons and have about the

same .

2. have much less mass than the other two particles in an atom.

3. Most of the mass of an atom is in the .

B. Different Elements—Different Numbers of Protons

1. The number of protons in an atom of an element is the

element’s .

2. Different elements contain different numbers of .

3. In a neutral atom, the number of equals the number of

protons because the number of charges must equal the

number of positive charges.

C. Neutrons and Isotopes

1. are atoms of the same element that have different

numbers of .

2. The total number of and neutrons in an atom is the

of the atom.

3. The of an element is the average mass of the

element’s .

a. The average atomic mass is according to the abundance of each isotope.

b. Weighted means that the average atomic mass is based on the

of each atom in a sample and the number of atoms

of that that are present.

D. Radioactivity

1. first noticed that some elements spontaneously give

off .

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ATOMIC STRUCTURE WORKSHEET Fill in the blanks. Use your periodic table. Round up atomic mass if necessary.

1. Atomic Number for Copper _______________

2. Number of electrons for Sulfur __________________

3. Number of protons for Hydrogen _________________

4. Atomic mass for Oxygen ____________________

5. Number of electrons for Phosphorous _____________________

6. Atomic number for Helium _______________________

7. Number of protons for Lithium _____________________

8. Atomic mass for K _________________________

9. Number of protons for Be _________________________

10.Number of neutrons for Ni ________________________

11.Atomic number for C _______________________

12.Number of protons for Fe ___________________

13.Atomic mass for Cl ___________________

14.Atomic number for Na ________________________

15.Number of electrons for N _________________________

16.This element has 9 protons ___________________

17.This element has 80 electrons ___________________

18.This element has an atomic number of 46 _______________________

19.This element has an atomic number of 18 _______________________

20.This element has 5 electrons _______________________

21. This element has 12 protons _______________________

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Alpha Decay An alpha particle is made of two protons and two neutrons. When an atom releases an alpha particle, its atomic number decreases by two. Uranium-238 decays to thorium-234 through the process of alpha decay.

Beta Decay In beta decay, a neutron in an atom changes into a proton and a high-energy electron called a beta particle. The new proton becomes part of the nucleus. The beta particle is released. In beta decay, the atomic number of an atom increases by one because it has gained a proton.

Gamma Decay Gamma rays do not contain particles, but they do contain a lot of energy. In fact, gamma rays can pass through thin sheets of lead! Because gamma rays do not contain particles, the release of gamma rays does not change one element into another element.

Uses of Radioactive IsotopesThe energy released by radioactive decay can be harmful

as well as beneficial to humans. Too much radiation can damage or destroy living cells, making them unable to function properly. Some organisms contain cells, such as cancer cells, that are harmful to the organism. Radiation therapy can be beneficial to humans by destroying these harmful cells.

Ions—Gaining or Losing ElectronsWhat happens to a neutral atom if it gains or loses

electrons? Recall that a neutral atom has no overall charge. This is because it contains equal numbers of positively charged protons and negatively charged electrons. When electrons are added to or removed from an atom, that atom becomes an ion. An ion is an atom that is no longer neutral because it has gained or lost electrons. An ion can be positively or negatively charged, depending on whether it has lost or gained electrons.

Positive IonsWhen a neutral atom loses one or more electrons, it has

more protons than electrons. As a result, it has a positive charge. An atom with a positive charge is called a positive ion. A superscript plus sign (+) following the element’s symbol represents a positive ion. For example, the top half of the figure on the next page shows how sodium (Na) becomes a positive sodium ion (Na+).

Key Concept Check10. Describe What happens during radioactive decay?

Reading Check12. Differentiate How is an ion different from a neutral atom?

11. Apply Why do people who work with radioactive materials wear special protective clothing?

172 Understanding the Atom Reading Essentials

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Negative IonsWhen a neutral atom gains one or more electrons, it has

more electrons than protons. As a result, the atom has a negative charge. An atom with a negative charge is called a negative ion. A superscript negative sign (-) following the element’s symbol represents a negative ion. The bottom half of the figure above shows how fluorine (F) becomes a fluorine ion (F-).

Key Concept Check 14. Explain How does a neutral atom change when its number of protons, electrons, or neutrons changes?

Visual Check13. Evaluate Why does a fluorine ion have a negative charge?

Formation of Positive and Negative Ions

+ + + + + + + + +- - - - - - - - -

+ + + + + + + +- - - - - - - -

+ + + + + + + + +- - - - - - - - -

+-

+-

+ + + + + + + + +- - - - - - - - -

+-

+

+- -

11 protons

10 electrons

9 protons

10 electrons

9 protons

9 electrons

11 protons

11 electrons

Sodium atom (Na)

Fluorine atom (F)

Sodium ion (Na+)

Fluorine ion (F–)

Reading Essentials Understanding the Atom 173


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Negative IonsWhen a neutral atom gains one or more electrons, it has

more electrons than protons. As a result, the atom has a negative charge. An atom with a negative charge is called a negative ion. A superscript negative sign (-) following the element’s symbol represents a negative ion. The bottom half of the figure above shows how fluorine (F) becomes a fluorine ion (F-).

Key Concept Check 14. Explain How does a neutral atom change when its number of protons, electrons, or neutrons changes?

Visual Check13. Evaluate Why does a fluorine ion have a negative charge?

Formation of Positive and Negative Ions

+ + + + + + + + +- - - - - - - - -

+ + + + + + + +- - - - - - - -

+ + + + + + + + +- - - - - - - - -

+-

+-

+ + + + + + + + +- - - - - - - - -

+-

+

+- -

11 protons

10 electrons

9 protons

10 electrons

9 protons

9 electrons

11 protons

11 electrons

Sodium atom (Na)

Fluorine atom (F)

Sodium ion (Na+)

Fluorine ion (F–)

Reading Essentials Understanding the Atom 173


Directions: Answer the following questions in complete sentences

1. How is an ion different from a neutral atom? _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________

2. Why does a fluorine ion have a negative charge? ________________________________________________________________________________ ________________________________________________________________________________ ________________________________________________________________________________

3. How does a neutral atom change when its number of protons, electrons and neutrons changes?

_______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________ _______________________________________________________________________________

7th Grade Science

Atomic Mass and Atomic Number

UNIT 1

LESSON 11

Exit Ticket

Name_____________________________________ Date:_____________________________________

Directions: On each line write the term from the word bank that correctly completes each sentence. Not all terms are used!

1. The ____________________________ is a weighted average that reflects the abundance of different isotopes.

2. The ______________________________ is determined by adding the number of protons and neutrons in an atom.

3. __________________________ are atoms of the same element that have different numbers of neutrons.

4. An element’s ____________________________ and the number of protons in the nucleus of its atoms are always the same.


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Name Date Class

Chapter Test B continued

CompletionDirections: One each line, write the term from the word bank that correctly completes each sentence. Not all terms are used.

atomic number average atomic mass elements

ions isotopes mass number

neutrons nucleus protons

7. The is a weighted average that reflects the abundance of different isotopes.

8. The is determined by adding the number of protons and neutrons in an atom.

9. are atoms of the same element that have different numbers of neutrons.

10. always have a positive or negative charge.

11. An element’s and the number of protons in the nucleus of its atoms are always the same.

Interpreting a Table Directions: Complete this table by choosing terms from the word bank and writing them in the correct spaces. Not all terms are used.

1 high-energy electron 1 proton 2 protons and 2 neutrons

decreases by 2 decreases by 1 energy

increases by 1 increases by 2 none

Type of Decay

What Is Released?

Released Material Consists of

New Element Formed?

Change in Atomic Number

alpha decay

alpha particle

12. yes 13.

beta decay

beta particle

14. yes 15.

gamma decay

gamma ray 16. no 17.

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