The Atom.

The Atom

Essential Question? Compare and contrast the characteristics of an atom and function of these characteristics in an atom?

Structure of an Atom

Proton p+ The Atomic # always equals the # of protons
Positive Charge (p+) Located in the nucleus Mass of a proton = x 10-24g Relative Mass 1 amu Function: Gives an atom its identity – If the # of protons changes so does the type of atom Ex: Hydrogen has 1 proton Helium has 2 protons Lithium has 3 protons The Atomic # always equals the # of protons Ex: Hydrogen has an Atomic # = 1 and has 1 proton Proton

Neutron no No charge Located in the nucleus
Mass of a neutron x 10-24g Relative Mass = 1 amu Function: Adds mass to nucleus Mass # - Atomic # = # of no Ex: 1-1=0 hydrogen has 0 no

Electron e- Negative charge
Has very small mass (9.109 x 10-28g) and is not included in the atomic mass of the atom Relative Mass = 1/1840 Located outside the nucleus - electron cloud - orbitals - shells - energy levels Ex: Hydrogen has 1e- Function: Is responsible for an atoms behavior Electron

Atomic # = # protons = # electrons
Which element has 32 protons? Symbol__ Name __ Which element has 14 protons? Symbol__ Name __ The mass number is the number of protons PLUS the number of neutrons in an atom. This is because the mass of the atom is mainly inside the nucleus where the protons and neutrons are found. The mass number – protons = number of neutrons on the Periodic Table

Find and Round the Atomic Mass to the nearest whole number
Element Symbol Average Atomic Mass Mass Number (round # up or down) Ca Barium Cl Nickel

Find and Round the Atomic Mass to the nearest whole number
Element Symbol Average Atomic Mass Mass Number (round # up or down) Calcium Ca 40.1 amu 40 amu Barium Ba 137.3 amu 137 amu Chlorine Cl 35.5 amu 36 amu Nickel Ni 58.7 amu 59 amu

Three types of atoms

This will help you determine which type of atom you have
If the p+ ≠ e- then you have an ION If you add the p+ + no & the mass # ≠ the mass on the PT, you have an ISOTOPE If the mass # = the mass # on the PT, and the p+ = e- then you have an Element

Element Cannot be broken down into simpler substances by physical or chemical means Each has a symbol located on the Periodic Table Ex: Ag – Silver, Pb – Lead Each has an atomic # and atomic mass Ex: Ag – Atomic # = 47 Atomic mass = amu Pb – Atomic # = 82 Atomic mass = amu Atomic # = # of p+ = # of e- If the # of p+ = the # of e- the atom is electrically neutral Atomic mass = # of p+ + # of no (this number must match the rounded atomic mass (or Mass #) on the periodic table)

Element - Fill in the table below
Atomic # Protons Neutrons Electrons Mass # H He Li Be B C N O F Ne

Element Fill in the table below
Atomic # Protons Neutrons Electrons Mass # H 1 He 2 4 Li 3 7 Be 5 9 B 6 11 C 12 N 14 O 8 16 F 10 19 Ne 20

Ion An ion is an atom with a charge. The charge is either positive or negative The charge depends on if the electrons are donated (lost) or accepted (gained) Ex: If an atom donates e- then the charge becomes positive (+) Na+ Ex: If an atom accepts e- then the charge becomes negative (-) Cl- To identify an ion the # of protons will NOT equal the # of electrons Ex: Cl normally has 17e- A Cl- ion has 18e- (Cl has accepted 1e-)

Ion - Fill in the table below
Element Protons Electrons Gained or Lost e-? H Li 2 Be B N 8 O 9 F 10

Ion - Fill in the table below
Element Protons Electrons Gained or Lost e-? H 1 Lost Li 3 2 Be 4 B 5 N 7 8 Gained O 9 F 10 Are the number of protons and electrons the same or different? DIFFERENT

Mass number – Atomic number = # of no
Isotopes Are atoms with the same number of protons but has a different number of neutrons than the normal number of neutrons in an atom To calculate the # of no round the atomic mass to the nearest whole number then subtract the atomic number. When the atomic mass is rounded it is called the Mass number Mass number – Atomic number = # of no Ex: (Pb) 207 – 82 = 125 neutrons If the atom is an isotope then there will be more neutrons and the mass will be more Ex: (Pb) 208 – 82 = 126 neutrons Isotopes are neutron rich and unstable

Isotopic Notation Si Isotopic Name Silicon-28 Ex: Silicon 28 14 Mass #
Atomic # Isotopic Name Silicon-28 Mass #

Let’s Compare the Following
Carbon-12 Carbon-13 Carbon-14 Atomic # Protons Electrons Mass Number Neutrons

Let’s Compare the Following
Carbon-12 Carbon-13 Carbon-14 Atomic # 6 Protons Electrons Mass Number 12 13 14 Neutrons 7 8 How are the notations alike? How are the above notations different? Same protons and electrons Different Mass # & neutrons

Review Answer questions 1-5 in Part I Answer questions 6-10 in Part II
Isotopes are atoms of the same element with the same number of _______, but with different numbers of _______. Answer questions 1-5 in Part I Answer questions 6-10 in Part II

Complete Isotopes or Different Elements WS Front and back
# Statement Element(s) Different Element, Isotope 1 Element D has 6 protons and 6 neutrons Element F has 7 protons and 7 neutrons 2 Element J has 27 protons and 32 neutrons Element L has 27 protons and 33 neutrons 3 Element X has 17 protons and 18 neutrons Element Y has 18 protons and 17 neutrons 4 Element Q has 56 protons and 81 neutrons Element R has 56 protons and 82 neutrons 5 Element T has an atomic # of 20 and an atomic mass of 40 Element Z has an atomic # of 20 and an atomic mass of 41 6 Element W has 8 protons and 8 neutrons Element V has 7 protons and 8 neutrons 7 Element P has an atomic # of 92 and an atomic mass of 238 Element S has an atomic # of 92 and an 143 neutrons

Complete Isotopes or Different Elements WS Front and back
# Statement Element(s) Different Element, Isotope 1 Element D has 6 protons and 6 neutrons Element F has 7 protons and 7 neutrons Carbon Nitrogen DE 2 Element J has 27 protons and 32 neutrons Element L has 27 protons and 33 neutrons Cobalt - 59 Cobalt - 60 Isotope 3 Element X has 17 protons and 18 neutrons Element Y has 18 protons and 22 neutrons Chlorine Argone 4 Element Q has 56 protons and 81 neutrons Element R has 56 protons and 82 neutrons Barium - 137 Barium - 138 5 Element T has an atomic # of 20 and an atomic mass of 40 Element Z has an atomic # of 20 and an atomic mass of 41 Calcium - 40 Calcium - 41 6 Element W has 8 protons and 8 neutrons Element V has 7 protons and 7 neutrons Oxygen 7 Element P has an atomic # of 92 and an atomic mass of 238 Element S has an atomic # of 92 and an 143 neutrons Uranium - 238 Uranium - 235

Fill in the Chart Below Element Symbol Atomic # Mass # # of p+ # of no
# of e- Helium 24 30 31 Br 13 U 11 12 Krypton Ca Ag 61

Fill in the Chart Below Element Symbol Atomic # Mass # # of p+ # of no
# of e- Helium He 2 4 Magnesium Mg 12 24 Zinc Zn 30 65 35 31 Bromine Br 80 45 Aluminum Al 13 27 14 Uranium U 92 238 146 Sodium Na 11 23 Krypton Kr 36 84 48 Calcium Ca 20 40 Silver Ag 47 108 61

Summarize Fill in Part V chart

Fill in the Chart Below Isotopic Notation Isotopic Name Atomic #
# of p+ # of no # of e- Mass # Zinc-67 17 36 Lead-207 99 155 94 244 Thallium-210

# of p+ # of no # of e- Mass # 80 205 78 200 Tungsten-191 79 112

# of p+ # of no # of e- Mass # Bromine-80 35 45 80 Zinc-67 30 37 67 Chlorine-53 17 36 53 Lead-207 82 125 207 Einsteinium-155 99 56 155 Plutonium-244 94 150 244 Fermium-260 100 160 260 Thallium-210 81 129 210

# of p+ # of no # of e- Mass # Mercury-205 80 125 205 Francium-232 87 145 232 Platinum-200 78 122 200 Tungsten-191 74 117 191 Gold-112 79 33 112

Answer questions part VI
Summarize Answer questions part VI

Part VII Potassium K – 39 has 20 neutrons K – 40 has 21 neutrons

Atomic Mass Determination
Chemist have developed a method of measuring mass of an atom called: Atomic Mass Determination Unit is abbreviated “amu” They did this because the masses of subatomic particles are so small that even scientific notation makes it hard to calculate the masses of elements. The atomic mass that you see on the PT is the average mass for the isotopes of that element. The atomic mass you see on the PT is also the isotope that is most abundant in nature!!! Answer Question 1 & 2

How is Atomic Mass Calculated?
The mass on the Periodic Table is the average mass of the isotopes of an atom To determine the atomic mass of an atom use this formula (Mass (amu) x Percent abundance)= Isotope A (Mass (amu) x Percent abundance)= Isotope B Add A + B / 100 = atomic mass

Example Problem #1 Calculate the atomic mass of the unknown element. Then identify the element using the Periodic Table? Isotope Isotopic Notation Mass (amu) Percent Abundance 185X 37.40 187X 62.60

6917.35 amu trace/least abundant +11703.45 amu most abundant
( amu x 37.40) = amu ( amu x 62.60) = amu amu trace/least abundant amu most abundant / 100 = amu Rhenium = Re

Which Isotope is trace and which is more abundant?
Practice Problem #2 Calculate the atomic mass of the unknown element. Then identify the element? Isotope Isotopic Notation Mass (amu) Percent Abundance 113X __?__ 115X 95.70 Which Isotope is trace and which is more abundant?

485 amu trace/least abundant +10996.3128 amu most abundant
( amu x ) = 485 amu ( amu x 95.70) = amu amu trace/least abundant amu most abundant / 100 = amu Indium = In

Practice Problems (Book)
Pp #15 Boron has 2 naturally occurring isotopes: boron-10(abundance = 19.8%, mass = amu), boron-11 (abundance = 80.2 %, mass = amu) Calculate the atomic mass of boron. #16 Helium has 2 naturally occurring isotopes, helium-3 and helium-4. The atomic mass of helium is amu. Which isotope is more abundant in nature? Explain #17 Calculate the atomic mass of magnesium. The three magnesium isotopes have atomic masses and relative abundances of amu (78.99%), amu (10.00%), amu (11.01%).

Practice Problem #1 Isotope Mass (amu) Percent Abundance 10B 10.013
Isotopic notation Mass (amu) Percent Abundance 10B 10.013 19.8 11B 11.009 80.2 5 5 Answer = amu

Practice Problem #2 Isotope Mass (amu) Percent Abundance 107Ag 106.9
Isotopic Notation Mass (amu) Percent Abundance 107Ag 106.9 51.82 109Ag 108.9 48.18 47 47 Answer = amu

Practice Problem #3 Isotope Mass (amu) Percent Abundance 24Mg 23.985
Isotopic Notation Mass (amu) Percent Abundance 24Mg 23.985 78.99 25Mg 24.986 10.00 26Mg 25.982 11.01 12 12 Answer = amu 12

Practice Problem #4 Helium-4 is most abundant b/c its mass is closer to the average atomic mass on the PT Helium-3 mass is not as close as Helium-4, so Helium-3 is less abundant

Practice Problem #5 Isotope Mass (amu) Percent Abundance 20Ne 19.992
Isotopic Notation Mass (amu) Percent Abundance 20Ne 19.992 90 22Ne 21.991 10 10 10 Answer = amu

Practice Problem #6 Isotope Mass (amu) Percent Abundance 176Hf 176
Isotopic Notation Mass (amu) Percent Abundance 176Hf 176 5.00 177Hf 177 19.0 178Hf 178 27.0 179Hf 179 14.0 180Hf 180 35.0 72 72 72 72 72 Answer = amu

Practice Problem #7 Isotope Mass (amu) Percent Abundance 28Si 27.977
Isotopic Notation Mass (amu) Percent Abundance 28Si 27.977 92.21 29Si 28.976 4.70 30Si 29.975 3.09 14 14 14 Answer = amu

Practice Problem #8 Isotope Mass (amu) Percent Abundance 107Ag 106.905
Isotopic Notation Mass (amu) Percent Abundance 107Ag 51.83 108Ag 48.17 47 47 Answer = amu

Practice Problem #9 Isotope Atomic # Mass (amu) Neon-20 10 19.992
Isotopic Name Atomic # Mass (amu) Neon-20 10 19.992 Neon-21 20.994 Neon-22 21.991 Answer = Neon-20 Why? Its mass is closest to the average mass of neon on the PT.

Practice Problem #10 Isotope Mass (amu) Percent Abundance 78Kr 77.920
Isotopic Notation Mass (amu) Percent Abundance 78Kr 77.920 0.350 80Kr 79.916 2.27 82Kr 81.913 11.56 83Kr 82.914 11.55 84Kr 83.912 56.90 86Kr 85.911 17.37 36 36 36 36 36 Answer = amu 36

How was the Atom Discovered?
Fill in Atomic Theory WS Use your book Many early philosophers thought matter was made up of 4 components Earth – Air, Fire – Water

Democritus’s Ideas (384-322 B.C.)
Matter is composed of empty space through which atoms move Atoms are solid homogenous, indestructible & indivisible Different kinds of atoms have different sizes & shapes The differing properties of matter are due to the size, shape and movement of atoms Apparent changes in matter result from changes in the grouping of atoms and not from the changes in atoms themselves

Dalton’s Ideas ( ) All matter is composed of extremely small particles called atoms All atoms of a given element are identical, having the same size, mass and chemical properties. Atoms of a specific element are different than those of any other element. Atoms cannot be created, divided into smaller particles or destroyed. Different atoms combine in simple whole ratios to form compounds In a chemical reaction, atoms are separated, combined or rearanged.

Mendeleev’s Contribution
Developed the Periodic Table Arranged the Periodic Table based on atomic mass

Roentgen’s Discovery X-Rays – invisible rays of e- bombarding the surface of materials Noticed this mysterious radiation passed through soft tissue, but not bone or metals

Currie’s Discovery Radioactivity – radiation Found Polonium, Radium

Bacquerel’s Contribution
Phosphorescent minerals – uranium salts exposed photographic plates in dark Found that uranium naturally emits radiation

J. J. Thomson’s Discovery
Determine the mass ratio of particles Said Dalton was wrong Found e-

Thompson’s Concept of the Atom
Plum Pudding Model Negatively charged electrons were distributed throughout a uniform positive charge

Cathode Ray Experiment William Crookes – Accidentally found Lead to the invention of the TV, Computer monitors (Radiation hits light producing chemicals on the backsides of screens) Vacuum tube – low pressure – Electric charge (-) cathode passes to (+) anode – light is electrons React to magnets Light is a stream of charged particles Particles have a (-) charge Found a particle smaller than the H atom by looking at known charge to mass ratios. WS – Cathode Ray Experiments

Rutherford’s Contribution (1871-1937)
Found Nucleus Nucleus has a (+) charge Devised a way with H. G. Moseley to bombard elements with a cathode ray which they used to assign atomic numbers to elements Found - Alpha, Beta, Gamma radiation

Rutherford’s Gold Foil Experiment
Narrow beam of alpha particles was a thin sheet of gold foil. Zinc sulfide screen surrounding the gold foil produced a flash of light whenever it was struck by an alpha particle

WS – Understanding Rutherford’s Gold Foil Experiment
The deflection was the alpha particle bouncing off the nucleus WS – Understanding Rutherford’s Gold Foil Experiment

Bohr’s Contribution (1885-1962)
Model of an atom Small orbit = lower energy state or energy level Part of the Manhattan Project Advocate for safe use of Atomic energy

Chadwick’s Discovery Neutron No Charge Mass almost = to mass of proton

Definitions Atomic Mass – total average mass of an atom
Atomic number - # of p+, in an atom Mass Number – total # of p+, & no Atom – Smallest particle in an element, electrically neutral, spherically shaped and composed of p+, no and e- Ion – An atom or bonded group of atoms w/ a (+) or (-) charge. Isotope – atoms of the same element w/ different # of no

Complete the Following Table
Element Symbol Element, Ion, Isotope Atomic # Mass # Protons neutrons electrons B Sulfur 7 Chlorine 18 Carbon-14 31 15 13 Iodine-128 22

Complete the Following Table
Element Symbol Element, Ion, Isotope Atomic # Mass # Protons neutrons electrons Boron B E 5 11 6 Sulfur S 16 32 Nitrogen N 7 14 Chlorine Cl Ion 17 35 18 Carbon-14 C-14 Isot 8 Phosphorus P 15 31 Aluminum Al 13 28 Iodine-128 I-128 Iso 53 128 75 Argon Ar 40 22

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