Parts of an Atom

Part 1: Subatomic Particles & Parts of the Atom

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3 SUBATOMIC PARTICLES:

• PROTONS have a positive charge (+).

  • (Hint: Protons and Positive start with the same letter!)

• NEUTRONS are neutral (almost the same word). (0)

  • Neutral means no charge.

• ELECTRONS have a negative charge (-).

​p⁺




n⁰



e^-

2 Main Regions: Nucleus and Electron Cloud

Nucleus: The central core of the atom. It contains protons (+ charge) and neutrons (no charge).

Electron Cloud: The region surrounding the nucleus. It is divided into energy levels (blue circles) and contains electrons (- charge).

CHARGES:
The protons & electrons are responsible for the charges.

• NUCLEUS: It has a positive charge because it contains protons.

• ELECTRON CLOUD: It has a negative charge because it contains electrons.

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CHARGES:
The protons & electrons are responsible for the charges.

• ENTIRE ATOM: It has a neutral charge because the nucleus and the electron cloud cancel each other out.

Take a minute to use the notes you just filled in to complete the box labeled "Take Away Ideas" to finish up Part 1.

Multiple Choice

What are the two main regions of an atom?

• Protons and electrons

• Nucleus and electron cloud

• Neutrons and electrons

• Nucleus and protons

Multiple Choice

What is the overall charge of an entire atom?

• Positive charge

• Negative charge

• Neutral charge

• No charge

Match

Match each subatomic particle or location in the atom with its appropriate charge.

• Electron

• Proton

• Neutron

• Nucleus

• Electron cloud

negative

positive

neutral

positive

negative

• negative

• positive

• neutral

• positive

• negative

Part 2: Identifying an Element

IDENTITY OF AN ATOM:  

Determined ONLY by the number of protons in the nucleus

​Neutrons & electrons have nothing to do with the identity of the atom

Atomic Number

The number of protons in an atom

Whole number at the top of the box on the PT

Multiple Choice

Use your periodic table to identify which element this represents.

• silver

  symbol = Ag

• iron

  symbol = Fe

• titanium

  symbol = Ti

• tungsten

  symbol = W

Multiple Choice

Use your periodic table to identify which element this represents.

• niobium

  symbol = Nb

• uranium

  symbol = U

• copper

  symbol = Cu

• oxygen

  symbol = O

Multiple Choice

Use your periodic table to identify which element this represents.

• mercury

  symbol = Hg

• uranium

  symbol = U

• oxygen

  symbol = O

• bromine

  symbol = Br

Different # of protons = Different element

Multiple Choice

Which element has 1 proton?

• hydrogen, H

• lithium, Li

• carbon, C

• nickel, Ni

Multiple Choice

How many protons does a helium atom have?

• 1

• 2

• 4

• 7

Multiple Choice

Which element has 6 protons?

• hydrogen, H

• lithium, Li

• carbon, C

• nickel, Ni

Multiple Choice

How many protons does a calcium atom have?

• 2

• 4

• 20

• 40

The elements are arranged in order based on increasing atomic number (#p⁺).

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Organization of the Periodic Table:

Use your PT to complete this chart.

Ask me to check your work before you move on.

Take a minute to use the notes you just filled in to complete the box labeled "Take Away Ideas" to finish up Part 2.

Part 3: The Stability of the Nucleus

Protons and neutrons are packed tightly together in the nucleus.

The ratio of protons to neutrons determines if a nucleus of an atom is STABLE or UNSTABLE.

​Atoms that have about the same number of protons & neutrons are STABLE.     

Their nuclei have no reason to change.

                                                                                 

Atoms that have very different numbers of protons & neutrons are UNSTABLE.     

Their nuclei will likely change and become stable by undergoing radioactive decay.

​1:1 ratio






NOT a 1:1 ratio

Categorize

Options (6)

1 proton, 1 neutron

2 protons, 2 neutrons

3 protons, 3 neutrons

1 proton, 2 neutrons

2 protons, 4 neutrons

3 protons, 5 neutrons

Organize these options into the right categories

Stable

Unstable

Take a minute to use the notes you just filled in to complete the box labeled "Take Away Ideas" to finish up Part 3.

Part 4: The Mass of Atoms

Mass Number

The total number of subatomic particles (p⁺ + n⁰) in the nucleus of one particular atom.

Use the Mass Number & Atomic Number to Calculate Neutrons:

You can determine the number of NEUTRONS an
atom has if you subtract the number of protons
from the total number of particles in the nucleus.

Multiple Choice

How many neutrons are found in an element with a mass number of 27 and 13 protons?

• 13

• 14

• 27

• 40

​ELECTRONS DON’T COUNT – too tiny!

Just about all of the mass of an atom in found in the nucleus. 

Electrons are MUCH TOO tiny to have any impact on the MASS of an atom. 

     Analogy: Imagine standing on a scale.  Would your weight change
if a speck of dust lands on your shoulder?  NO!  

                Think of electrons like specks of dust.  They do not
contribute to the mass of an atom.

MASS NUMBER is NOT on the Periodic Table: 

An individual atom’s  MASS NUMBER and the number written on the bottom of each box on the Periodic Table are not the same thing. 

Mass Number = total mass (number of p⁺ and n⁰) in ONE specific atom of an element        

​is NOT the same as

MASS NUMBER is NOT on the Periodic Table: 

The number on the bottom of a box on the PT = Average Atomic Mass = the average of all the mass numbers for every atom of an element. 

    

MASS NUMBER and AVERAGE ATOMIC MASS are related but not the same thing. When asked about the MASS NUMBER, do NOT even look at the Periodic Table.  Just add the protons and neutrons in one particular atom together. 

Use the information provided and your PT to complete this chart.


Ask me to check your work before you move on.

Multiple Select

Which subatomic particle(s) is/are included in the mass of an atom?

• electrons

• protons

• neutrons

Take a minute to use the notes you just filled in to complete the box labeled "Take Away Ideas" to finish up Part 4.

Part 5: Isotopes & Isotope Name

ISOTOPES are atoms of the same element that have different MASS NUMBERS because they contain different numbers of NEUTRONS in the nucleus. 

​PART 5:  ISOTOPES & ISOTOPE NAME

​Analogy:   Isotopes are like the

same kind of animal (same element) but different weights (masses)

Multiple Choice

Which of the following is NOT an isotope of the other two answer choices?

• An atom with 6 protons and 6 neutrons.

• An atom with 5 protons and 7 neutrons.

• An atom with 6 protons and 7 neutrons.

All three atoms are atoms of Magnesium because they each contain 12 protons.

They each have different number of neutrons and therefore a different mass number. 

They are “isotopes” of magnesium.

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​ISOTOPE NAME: 
name or chemical symbol followed by a dash (-) and the MASS NUMBER of that particular atom  

​lithium 6 lithium 7 beryllium 7

Apply what you have learned to complete the practice.



Ask me to check your work before you move on.

Take a minute to use the notes you just filled in to complete the box labeled "Take Away Ideas" to finish up Part 5.

Multiple Choice

What is the correct isotope name for an atom that contains 9 protons and 10 neutrons?

• neon-10

• neon-19

• fluorine-9

• fluorine-19

​You have finished this lesson!

You will complete the Check-in during our next class period.