Atom Activity Model - s3.eu-west-2.amazonaws.com€¦ · This atom model can be used to demonstrate the atom structure of most elements. Some of the elements you may choose include

Neo/SciTeacher’s GuideNeo/SCI™

Teacher’s Guide

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Objectives

• Study the structure of an atom and the relationships among protons,neutrons and electrons.

• Construct an atom model with a central nucleus and orbiting electrons.

• Demonstrate the formation of ions.

• Model the formation of molecules and compounds with covalent bonds.

• Demonstrate the formation of ionic bonds.

• Explain what determines the stability of an atom.

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Atom Activity Model

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Neo/SciTeacher’s Guide

Science Concepts

Kit Materials List

• Atom

• Electrons

• Protons

• Neutrons

• Energy levels

• Covalent bonding

• Ionic bonding

30 Balls, blue wooden (neutrons)

30 Balls, green wooden (protons)

1 Container, transparent dome-shaped (nucleus)

1 Disc, transparent plexiglass (energy levels)

20 Pins, white plastic (electrons)

Materials Needed But Not Provided:Overhead projector (optional)

This lab activity uses small parts which may represent achoking hazard. Be sure that students follow directionsand follow precautions when working with these parts.

Safety & Disposal

If the model is to be used as a demonstration, place it onan overhead projector so that the electrons, protons andneutrons placed on it can be projected on a screen forthe entire class to view.

You can use this model to teach about elements 1-18,since the model only covers energy levels 1, 2, and 3.

Pre-lab Setup

Step 2

To demonstrate the structure of an atom with an outer-most energy level filled, assemble an atom model of theelement Neon (Ne). Place 10 protons (green balls) and10 neutrons (blue balls) in the nucleus of the model.Place two electrons (yellow pins) in the first energy leveland 8 in the second level.

Step 3

Assemble atom models of other elements of yourchoice, using the information from a "PeriodicTable of the Elements."

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Atom Activity Model

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Activity

Constructing an Atom Model

Lab Activity Procedures & Notes

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What to do. . .

This atom model can be used to demonstrate the atomstructure of most elements. Some of the elements youmay choose include H, Li, O, C, Cl, Ne, Na, among manyothers.

Step 1

To demonstrate the lithium atom using the activitymodel, place three protons (green balls) and four neu-trons (blue balls) in the nucleus of the model. Place twoelectrons (white pins) in the first energy level and one inthe second level.

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Lithium Atom

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—Neon Atom

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Questions

1. Based upon your representative atom model of lithi-um (Li), what is its atomic mass? What is the atomicmass of neon (Ne)?

Based on the model representation, the atomic massof Li is 7, whereas Ne has an atomic mass of 20.

2. Which of the two elements, lithium (Li) or neon (Ne), ismost stable? Explain.

Ne is a stable element since its outermost energylevel is filled, whereas neon's outermost energy levelis partially filled.

3. What is the valence number of lithium?

It is +1. The valence number of an atom is related tothe number of electrons in the outermost energylevel of an atom of that element. It is the number ofelectrons that the atom must gain or lose to achievea filled energy level. In this case lithium must loseone electron for its outermost energy level to befilled.

4. What is the most electrons that the first energy levelof an atom can hold? The second? The third?

The most electrons that the first energy level canhold is 2. The second and third levels can each hold8.

5. Why are some atoms unreactive?

Atoms that have their outermost energy level filledare stable and, therefore, unreactive.

6. Explain the relationships among protons, neutronsand electrons.

Protons are part of the nucleus and carry a positivecharge; neutrons are also part of the nucleus, buthave no electrical charge. The sum of the protonsand neutrons in the nucleus is known as the "atomicmass" of an atom. Electrons are negatively chargedand are arranged around the nucleus in energylevels.

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Activity

Forming Ions


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What to do. . .Normally, atoms are neutral - that is, they contain anequal number of positive charges (protons) and negativecharges (electrons). However, under certain conditions,such as input of energy, atoms can either gain or lose anelectron. When this occurs, the atom becomes electrical-ly charged and is called an "ion." Ions can either be neg-atively or positively charged, depending upon whetherthey have gained or lost electrons. The process of form-ing ions is called "ionization." Atoms with valence elec-trons that are not tightly held are said to have a low "ion-ization energy." A low ionization energy implies thatvery little energy is required to remove or add a valenceelectron.

Step 1

Construct a carbon (C) atom model by adding six pro-tons (green balls) and six neutrons (blue balls) to thenucleus of the model. Place two electrons (white pins) inthe first energy level and four in the second level.

Step 2

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Neutral carbon atom

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Remove one valence electron from the outermost ener-gy level. What is the charge of the carbon ion, since itlost an electron?

Step 3

Replace the electron in the outermost energy level thatyou removed in Step 2. Add another electron in the out-ermost energy level. What is the charge of the carbonion now, since it gained an electron?

Step 4

Assemble models of other ions, such as fluorine (F) andmagnesium (Mg).

Questions

1. What is the difference between an ion and an atom?

An ion is an atom with an electrical charge.

2. What would have to happen for a neutral atom tobecome a positive ion? To become a negative ion?

A neutral atom becomes a positive ion when it losesan electron. It becomes a negative ion when it gainsan electron.

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Neutral carbon atom C+1 ion Neutral carbon atom C+1 ion

Free Electron

Free Electron

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Activity

Forming Covalent Bonds


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Some molecules are formed by atoms that share theirvalence electrons. When sharing of valence electronsoccurs, a "covalent bond" results between the twoatoms. The sharing of valence electrons allows the out-ermost energy levels of both atoms to be filled. Thissharing of electrons provides the atoms with a stablestructure. Common gases such as hydrogen, oxygen andnitrogen are held together by covalent bonds, as arecompounds such as water, carbon dioxide and ammonia,among many others.

Note: You will need at least 2 atom models to demonstratecovalent bonding between atoms, depending on the num-ber of atoms involved.

What to do. . .

Step 1

Construct a hydrogen (H) atom model, by adding 1 pro-ton (green ball) into the nucleus of the model. Place oneelectron (white pin) in the first energy level.

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Hydrogen Atom

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Water Molecule

Hydrogen

Hydrogen

Oxygen

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1. What causes a chemical bond to form?

A chemical bond is formed when two or more nucleiare attracting the same electrons.

2. How are electrons distributed in a covalent bond?

In a covalent bond, one or more electrons are sharedbetween two atoms.

Questions

Step 2

Construct a chlorine (Cl) atom model by adding 17 pro-tons (green balls) and 18 neutrons (blue balls) into thenucleus of the model. Place two electrons (white pins) inthe first energy level, eight in the second level and sevenin the third level.

Step 3

Bring the two atoms models together so that the elec-tron on the H atom is shared with the outermost energylevel of the Cl atom. By sharing electrons, the chlorineatom now has the eight electrons required to fill its out-ermost energy level. The same holds true for H, whichnow has the 2 electrons required to fill its outermostenergy level.

Step 4

Assemble additional electron-sharing molecules, such aschlorine, hydrogen and oxygen molecules, and com-pounds such as water (H20) and ammonia (NH3)

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17 P18 N

Chlorine Atom

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—17 P18 N

HCl

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Activity

Forming Ionic Bonds


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The atom of sodium (Na), which has a low ionizationenergy, can combine with an atom of chlorine, which hasa high affinity for electrons, by transferring a valenceelectron from its outer energy level to the outermostenergy level of the chlorine atom. By losing itsoutermost electron, sodium becomes a Na+ ion. Bygaining one electron, the chlorine atom becomes a Cl-

ion. The sodium ion now has a net positive charge (10negative charges or electrons vs. 11 positive charges orprotons), whereas the chlorine ion now has a netnegative charge (18 negative charges or electrons vs. 17positive charges or protons). An ionic bond is formedbetween the sodium and the chlorine atoms, sincechlorine has captured an electron from the sodium. Thetwo ions formed, sodium and chlorine, are attracted toeach other because of their opposite charges.

Note: You will need 2 individual atom models todemonstrate the formation of ionic bonds.

What to do. . .

Step 1

Construct a sodium (Na) atom model by adding 11protons (green balls) and 12 neutrons (blue balls) to thenucleus of the model. Place two electrons (white pins) inthe first energy level, eight in the second level and one inthe third level.

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11 P12 N

Sodium AtomAtom

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Step 2

Construct a chlorine (Cl) atom model by adding 17 pro-tons (green balls) and 18 neutrons (blue balls) to thenucleus of the model. Place two electrons (white pins) inthe first energy level, eight in the second level and sevenin the third level.

Step 3

Illustrate the formation of an ionic bond by removing anelectron from the sodium atom and adding it to theouter energy level of the chlorine molecule. Notice thatthe outer energy level of the chlorine atom is now filled.

1. What happens to the outermost energy level whenionic compounds are formed?

When ionic compounds are formed, the outermostenergy level of each ion is filled.

2. How does an ionic bond differ from a covalent bond?

The ions in an ionic bond attract each other, due totheir opposite electrical charges. In a covalent bond,the atoms share the electrons.

Questions

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17 P18 N

Chlorine Atom

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11 P12 N

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17 P18 N

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NaCl

Na+1 Cl-1

Atom Activity Model

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Cross-Curricular IntegrationAssessment

Students can be assessed on the concepts presented inthis investigation, using the questions that follow eachactivity. Additionally, students may be asked to use themodel to assemble various atom models and molecules.

Biology

Using the concepts of atom structure and bondformation, students may be further introduced tochemical reactions that occur in living organisms.Among them are respiration, photosynthesis, anddigestion of nutrients.

Math

Discuss with your students how chemists use thevalence electron number to predict how elements willcombine to form compounds.

History

Have students research the history of the atom theorystarting with the ancient Greeks to the present.

Atom Activity Model - s3.eu-west-2.amazonaws.com€¦ · This atom model can be used to demonstrate the atom structure of most elements. Some of the elements you may choose include

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