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Home , Isotopes of lithium

UNIT 1 SUMMARY MATTER – Anything that has mass and takes up space

Other examples?

PARTICLE – a single or groups of that are bonded together and function as one unit Matter is found in phases or states: GAS • Indefinite shape and volume • Straight-line motion LIQUID • Indefinite shape, definite volume • Rolling motion SOLID • Definite shape and volume • Vibrating motion

TYPES OF MATTER PURE SUBSTANCE – Matter where all the particles are identical

He

NaCl

C12H22O11 There are two types of pure substances: ELEMENT • Made from only one type of atom • Cannot be broken into simpler substances by chemical means • Found on the Periodic Table Other examples? COMPOUND • Made from two or more atoms joined together by chemical bonds • Can be broken down into simpler substances by chemical means (by breaking chemical bonds) Water Salt Sugar Other examples?

Water Compound ↓ electricity and ↓ electricity ↓ electricity Hydrogen and Oxygen Elements

Salt Compound ↓ electricity Sodium and ↓ electricity ↓ electricity Sodium and Chlorine Elements

In CHEMICAL SEPARATION METHODS (e.g. ), chemical bonds are broken and/or formed.

MIXTURE – Matter with different types of particles (elements and/or compounds) There are two types of mixtures: HETEROGENEOUS – Has distinct parts with different properties

HOMOGENEOUS – Has same properties throughout (uniform composition) Air Jell-O Steel Brass SOLUTION – A homogenous mixture

CLASSIFICATION OF MATTER

CHANGES IN MATTER PHYSICAL CHANGE – One that does not change the identity of the matter Tearing Crushing Freezing Melting Boiling

CHEMICAL CHANGE – One that does change the identity of matter through a CHEMICAL REACTION Burning Rusting Tarnishing Spoiling Exploding

EVIDENCE OF A CHEMICAL CHANGE • Color change • A solid forms • Bubbles are formed • A flame is produced • Heat is absorbed or released Are these physical or chemical changes? • Cookies are baked • Water boils • Soap dissolves in water • A firefly emits light • Milk spoils • A metal chair rusts More examples of physical and chemical changes?

CHEMICAL REACTION • Starting substance(s) called REACTANTS change into ending substances called PRODUCTS • Chemical bonds are broken and/or formed during the process

Compound Element Compound  Sugar  + Water Reactant Products CONSERVATION OF MASS – Mass is neither created nor destroyed

Reactants Product + Oxygen  Rust

Fe + O2  FeO 10 g 5 g 15 g

Mass of reactants = Mass of products Reactants? Products?

Methane + Oxygen  Carbon Dioxide + Water

CH4 + O2  CO2 + H2O 32 g 128 g 88 g ? THE ELEMENTS 400 BC The Ancient Greeks believed there were 4 elements: Earth, Wind, Fire, Water 2014 AD There are 118 known elements (98 exist naturally) SYMBOLS FOR THE ELEMENTS Each element is represented by an ATOMIC SYMBOL composed of 1-2 letter(s) 1st letter – always capital 2nd letter – always lower case Some symbols come from Latin names You do not need to memorize any atomic symbols, but you must be able to quickly identify them using a Periodic Table Co CO Carbon monoxide

Sn SN

Tin Sulfur & a little FORMULAS OF COMPOUNDS CHEMICAL FORMULA – The representation of a compound or molecule using atomic symbols Writing formulas: 1. Each element present is represented by its atomic symbol 2. A right subscript tells the number of atoms of each element 3. Subscripts of “1” are not written CS2 Na3AsO4 1 carbon atom 3 sodium atoms 2 sulfur atoms 1 atom 4 oxygen atoms

Zn(NO3)2 BaCl22H2O 1 atom 1 atom 2 nitrogen atoms 2 chlorine atoms 6 oxygen atoms 4 hydrogen atoms 2 oxygen atoms 400 BC – DEMOCRITUS Proposed that all matter is composed of particles ATOM comes from the Greek Atomos, meaning indivisible 1803 – JOHN Dalton’s Atomic Theory: 1. All matter is made of atoms 2. All atoms of a given element are the same 3. Atoms can combine in whole number ratios to form compounds 4. Atoms of one element cannot change into atoms of another element Because of Dalton’s atomic theory, most scientists in the 1800’s believed that the atom was a tiny solid ball that could not be broken up into parts.

DALTON MODEL OF THE ATOM

1897 – J. J. THOMSON Discovered electrons, indicating that atoms consist of subatomic particles ELECTRONS – Negatively charged subatomic particles

PLUM PUDDING MODEL OF THE ATOM

1910 – ERNEST RUTHERFORD Discovered that the atom has a small, positively charged core which contains almost all of the atom’s mass

RUTHERFORD MODEL OF THE ATOM

NUCLEUS – The dense, positive core of the atom that contains PROTONS – Positively charged subatomic particles

1932 – JAMES CHADWICK Discovered a third subatomic particle that is found in the nuclei of atoms –Neutral subatomic particles

NUCLEAR MODEL OF THE ATOM

Location Charge Relative Mass Nucleus + 1 Nucleus 0 1 Electron Around - 1/1836 Nucleus All atoms of a given element contain the same number of protons ATOMIC NUMBER (Z) – The number of protons in an atoms ← Atomic Number ← Atomic Symbol

Since atoms are electrically neutral, the number of electrons equals the number of protons

Any atom with 1 proton is a hydrogen atom

All 3 are hydrogen atoms because they each have 1 proton ISOTOPES – Atoms of the same element (same number of protons), but with different numbers of neutrons MASS NUMBER (A) – The sum of the protons and neutrons in an atom

Protons 1 1 1 Neutrons 0 1 2 Electrons 1 1 1 Mass Number 1 2 3

Nuclide Symbol 1H 2H 3H Name Hydrogen-1 Hydrogen-2 Hydrogen-3

Mass Numbers ARE NOT found on the Periodic Table Protons 2 2 Neutrons 1 2 Electrons 2 2 Mass Number 3 4

Nuclide Symbol 3He 4He Isotope Name Helium-3 Helium-4 PERIODIC TABLE An arrangement of the chemical elements in order of atomic number, with elements having similar properties placed in columns 1869 – DMITRI MENDELEEV Developed the first periodic table or SERIES – A row or FAMILY – A column Elements in columns have similar properties because they have the same number of valence electrons METALS Physical Properties – Metallic luster, malleable, ductile, conductors of heat and electricity Solids are brilliant white (or ) except (red) and gold (yellow); is a liquid

NONMETALS Physical Properties – Opposite of metals Some are crystalline solids, is a liquid, and some are gases METALLOIDS Properties of metals and nonmetals Border the diagonal line separating the metals and nonmetals Hydrogen - A group of its own Group 1 - Alkali Metals Group 2 - Alkaline Earth Metals Group 7 - Group 8 - Noble Gases Middle Block - Transition Metals Extra Block - Inner Transition Metals (Lanthanides and Actinides) Cu, Ag, Au, Pt - Noble Metals NATURAL Most elements are ACTIVE, so they easily form compounds Matter is mostly a mixture of compounds, not elements INERT elements can be found in their elemental form 1) Noble Metals : Cu, Ag, Au, Pt 2) Noble Gases : He, Ne, Ar, Kr, Xe, Rn To see any other element in its elemental state, compounds must be decomposed METALS

In their elemental state, metals consist of billions of atoms bonded together This strong chemical bonding causes most metals to be solids

NONMETALS

In their elemental state, most nonmetals consist of a small number of atoms bonded together, while a few consist of billions of atoms bonded together Molecules weakly attract, so molecular matter often exists in the gaseous state, but the molecules may attract each other enough to form solids or liquids 7 of the nonmetals that exist as molecules produce DIATOMIC MOLECULES Some elements have several forms in the elemental state

1) Oxygen : dioxygen (O2) and ozone (O3) 2) Carbon : diamond, graphite, buckminsterfullerene

ALLOTROPES – Different forms of a given element due to different interatomic bonding Atoms can gain or lose electrons ION – An atom with a positive or negative charge because it has gained or lost electrons

Lithium (Z = 3)

3 Protons 3 Protons 3 Electrons 2 Electrons

Lithium atom Lithium ion Li Li+ Li → Li+ + e- CATION – A positive ion Cations have the same name as their corresponding atom Cations are created when metals form compounds with nonmetals (Z = 9)

9 Protons 9 Protons 9 Electrons 10 Electrons

Fluorine atom ion F F- F + e- → F- ANION – A negative ion Anions are named with an –ide ending Anions are created when nonmetals form compounds with metals Many ion charges can be predicted from the Periodic Table

barium aluminum

Ba2+

bromide oxide phosphide Br- NUCLEAR MODEL OF THE ATOM

Location Charge Mass Proton Nucleus + 1.67310-27 kg Neutron Nucleus 0 1.67510-27 kg Electron Around - 9.11010-31 kg Nucleus MASS OF PROTON = 0.000000000000000000000000001673kg MASS OF ELECTRON = 0.000000000000000000000000000000911 kg Since subatomic particles are so small, an alternate unit is used to measure mass UNIT (amu or u) – One twelfth the mass of a carbon-12 atom 1 amu = 1 u = 1.6610-27 kg NUCLEAR MODEL OF THE ATOM

Location Charge Mass Proton Nucleus + 1.007 u Neutron Nucleus 0 1.009 u Electron Around - 0.0005486 u Nucleus ATOMIC MASS – The mass of an individual atom

Hydrogen-1 Hydrogen-2 Hydrogen-3 1.008 u 2.014 u 3.016 u

Use a reference table to find the atomic masses of different isotopes To generate these tables, a mass spectrometer was used to measure the atomic masses

MASS OF PROTON = 1.007 u  1 u MASS OF NEUTRON = 1.009 u  1 u The mass of a proton or neutron is approximately 1 u Atomic Mass  Mass Number

Hydrogen-1 Hydrogen-2 Hydrogen-3 1.008 u 2.014 u 3.016 u  1 u  2 u  3 u Each element has many different isotopes (same number of protons, but different numbers of neutrons) Each isotope has a unique atomic mass

Hydrogen-1 Hydrogen-2 Hydrogen-3 1.008 u 2.014 u 3.016 u Can an element have a single atomic mass if its isotopes each have different atomic masses???

← Atomic Number (Z)

← Atomic Symbol

← Atomic Weight (or Average Atomic Mass)

ATOMIC WEIGHT– The weighted average of the atomic masses of all of the element’s naturally occurring isotopes The atomic masses of individual isotopes are found in reference tables. The atomic weight of different elements are found on the periodic table. They can also be calculated…

To calculate atomic weight, for each isotope we need its atomic mass and its percent abundance PERCENT ABUNDANCE – The number of atoms of one isotope of an element divided by the total number of atoms of that element

99.985% of all naturally occurring Hydrogen atoms are Hydrogen-1, while 0.015% are Hydrogen-2

Atomic Mass % Abundance Hydrogen-1 1.0078 u 99.985% or 0.99985 Hydrogen-2 2.0147 u 0.015% or 0.00015 Hydrogen-3 3.0160 u 0 ATOMIC WEIGHT CALCULATIONS

ATOMIC WEIGHT = atomic mass of isotope 1 x percent abundance of isotope 1 + atomic mass of isotope 2 x percent abundance of isotope 2 + atomic mass of isotope 3 x percent abundance of isotope 3 (and so on…)

Atomic Mass % Abundance Hydrogen-1 1.0078 u 99.985% Hydrogen-2 2.0147 u 0.015% Hydrogen-3 3.016 u 0

Atomic Weight = (mass of 1H)(% 1H) + (mass of 2H)(% 2H) = (1.0078 u)(0.99985) + (2.0147 u)(0.00015) = 1.00764 u + 0.00030 u = 1.00794 u

By using a weighted average, isotopes with greater percent abundances contribute more heavily to the elemental atomic mass

Atomic Mass % Abundance Hydrogen-1 1.0078 u 99.985% Hydrogen-2 2.0147 u 0.015% Hydrogen-3 3.016 u 0

Note that the atomic weight of Hydrogen is much closer to the atomic mass of Hydrogen-1 than Hydrogen-2 because Hydrogen-1 is much more abundant than Hydrogen-2

Atomic Mass % Abundance Oxygen-16 15.99491 u 99.7587 % Oxygen-17 16.99913 u 0.0374 % Oxygen-18 17.99916 u 0.2039 % Atomic Weight = (mass of 16O)(% 16O) + (mass of 17O)(% 17O) + (mass of 18O)(% 18O) = (15.99491 u)(0.997587) + (16.99913 u)(0.000374) + (17.99916 u)(0.002039) = 15.95631 u + 0.006357 u + 0.036700 u = 15.9994 u

What are the abundances of the two naturally occurring isotopes of Lithium?

3 Atomic Mass % Abundance Lithium-6 6.015 u ???x Li Lithium-7 7.016 u 1???-x 6.94

Atomic Weight = (mass of 3Li)(% 3Li) + (mass of 4Li)(% 4Li) 6.94 = (6.015)(x) + (7.016)(1-x) 6.94 = 6.015x + 7.016 - 7.016x 1.001x = 0.076 x = 0.076  7.6% 1-x = 0.924  92.4%

MASS SPECTROMETRY – An analytical chemistry technique that measures the mass-to-charge ratio and abundance of ionized gas particles

Mass Spectrometer MOVING IONS IN MAGNETIC FIELDS A magnetic field will bend (or deflect) the path of a moving charged particle (like an ion) Higher charged particles deflect more Lower charged particles deflect less

z (lower case) = charge value Z (upper case) = atomic number Lighter particles deflect more Heavy particles deflect less

We can use the differences in deflection to separate particles of different charges and/or masses

The amount of deflection is determined by the particle’s mass to charge ratio (or m/z) We can use the differences in deflection to separate particles of different m/z MASS SPEC STEPS…

VAPORIZATION Mass spec only works for gas particles

IONIZATION Mass spec only works for charged particles

ACCELERATION Mass spec only works for moving particles

DEFLECTION

DETECTION

INTERPRETING MASS SPECTRA

Mass Spectrum for The horizontal location of a blue peak indicates the m/z ratio of the detected particles The height of the peak indicates how many particles were detected

Mass Spectrum for Molybdenum 7 separate peaks indicate that this sample of molybdenum has 7 different isotopes Assuming all ions have a charge of +1 (or z=+1), the atomic masses of the isotopes are 92, 94, 95, 96, 97, 98, and 100 amu

Mass Spectrum for Molybdenum Since the highest peak is at 98, the most abundance isotope in this sample is molybdenum-98

Mass Spectrum for Assume z=+1 for all ions… What are the ? What are the percent abundances of each isotope?

Mass Spectrum for Zirconium

Atomic Mass % Abundance Zirconium-90 90 amu 51.5 % Zirconium-91 91 amu 11.2 % Zirconium-92 92 amu 17.1 % Zirconium-94 94 amu 17.4% Zirconium-96 96 amu 2.8% Atomic Mass % Abundance Zirconium-90 90 amu 51.5 % Zirconium-91 91 amu 11.2 % Zirconium-92 92 amu 17.1 % Zirconium-94 94 amu 17.4% Zirconium-96 96 amu 2.8%

What is the (calculated) atomic weight of zirconium?

UNIT 1 TOPICS • Solid, liquid, gas • Periodic Table • Element, compound, mixture • Group names • Heterogeneous, homogeneous • Active and inert elements • Physical and chemical changes • Diatomic elements • Conservation of mass • Properties of metals, nonmetals, • Symbols for elements metalloids • Formulas of compounds • Allotropes • Scientist and their work • Cations and Anions • Atomic structure • Ion charges from the Periodic Table • Protons, neutrons, electrons • Elemental abundances • Atomic number, mass number • Atomic weight calculations • Isotopes • Mass spectrometry operation • Nuclide symbols • Mass spectrum interpretation