Chem Quiz #1 Flashcards
Define element
a type of matter composed of atoms w/ the same atomic # (substance can only correspond to 1 element on periodic table)
Allotrope
Diff. STRUCTURAL forms of the same element in the same phase
- diff. forms can have diff. reactivity
Examples of allotropes
Carbon: Diamond, graphite, & fullerenes
Oxygen: dioxygen (O2) & Ozone (O3)
Sulfur: orthorhombic, monoclinic, amorphous (30 others)
Phosphorus: red, white, & black
Photocatalytic water splitting
Uses sunlight to split H20, butt electrolysis energy doesn’t compensate for energy spent
Compound
substance that contains 2 or more elements
Binary compound
Contains 2 elements
Binary compound examples
H20, H202, CO, & CO2
Ternary compound
Contains 3 elements
Ternary compound examples
C2H5OH (ethanol)
Quaternary compound
Contains 4 elements
Polymorphs
Diff. structural forms of the same COMPOUND in the same phase
Polymorph examples
TiO2 (Anatase & Kutile)
Organic compound made w/
Carbon, Hydrogen, Oxygen, & sometimes Nitrogen
Prussian Blue
absorbs thallium & is treatment for radioactive exposure
Fe4[Fe(CN)6]3
Mixtures
Combination of 2 or more elements/compounds
Example of a mixture
Salt Water (NaCl + H20), Brass (Cu + Zn)
Heterogeneous
Can be physically separated (not uniform)
Heterogenous ex.
solid mixture of blue Cu(NO3)2 x 6H20 & yellow Cds
or
Cereal
Homogeneous
mixed @ molecular level butt NOT chemically bonded
- properties don’t vary through the sample
- can be separated butt not easily
Homogeneous ex.
NaCl + Water or air
Pure Substance
only an element or compound
Material
sample of unknown composition & may be a pure substance/mixture
Greek root of atom
atom (not) tomos (cut)
1st evidence for existence of atoms
analyzing weights of products & reactants
Law of Conservation of Mass
Mass is neither created nor destroyed in a chemical reaction
Law of Definite Proportions
In a pure compound, the constituent elements are always present in a set proportion or % by mass
Law of Constant Composition
All samples of a given chemical compound have the same elemental composition
- H20 is always 11.1% H & 88.9% no matter the source or method or prep
- lead sulfite is always lead sulfite…adding more just leaves leftover unreacted material
Dalton’s 5 Theories of Matter
- Elements consist of tiny indivisible particles called atoms (divisible by ionization
- All atoms of a given element are identical in mass & other properties
- Diff. elements have diff. atom kinds which have diff. masses
- Compounds are formed when atoms of unlike elements combine in small whole # ratios
- Atoms retain their identities in a chemical process & a chem. reaction just changes the atoms bonding
How are atoms divisible
Ionization & nuclear reactions
Law of Multiple Proportions
When 2 elements form a series of compounds, the masses of 1 element that combine w/ a fixed mass of the other element are in the ratio of small integers to each other
Law of Combining Gas Volumes
When gases (@ same pressure & temp.) react, they do so in a definite integer ration by volume. Volume of either reacting gas is the ratio of simple integers
Avogadro’s Hypothesis
Equal volumes of diff. gases @ same temp. & pressure contain equal # of particles. THe distances between the particles are very large, compared w/ the size of the particles
Avogadro’s Hypothesis ex.
1 L of hydrogen gas has the same # of particles as 1 L of oxygen gas or 1 : of nitrogen gas or 1 L of hydrogen chloride
Explain Avogadro vs Dalton beliefs
Dalton: believed particles of an elemental gas consisted of atoms
Avo: believed of an element gas could be atoms, diatomic, or polyatomic & could explain law of combining volumes
Cannizzaro findings
Calculated molecular mass of gaseous compounds & obtained a self-consistent set of relative atomic & molecular masses (accepted that these are diatomic molecules)
ex. if H2 is assigned a mass of 2, O2 is assigned a mass of 32 w/ a 16:1 Oxygen to Hydrogen ratio
Cannizzaro beliefs
- Molecules contain whole #’s of atoms
- Avogadro’s hypothesis is correct & equal volumes of gases under the same condition contain the same # of molecules (masses of equal volumes of gasses are proportional to the relative masses of the particles (atoms/molecules)
Relative molecular mass using Avo.’s hypothesis ex.
ratio of masses of equal volumes of oxygen & hydrogen is 16:1
Cannizzaro accepted
How to determine relative molecular masses of elements that aren’t gasses
study gaseous compounds of those elements
Physical structure of atoms
composed of + charged nucleus (protons & neutrons) and - electrons
facts abt protons
charge of P+ & e- are exactly the same
proton mass = neutron mass
proton mass = 1836 x electron
Evidence for electrons
Cathode/Beta rays
Cathode/Beta Rays
stream of electrons that could be deflected by magnetic & electric fields
OG name for electrons
corpuscles
charge to mass ratio of an electron
e/Me = -1.76x10^8 C/g
Millikan’s Oil Drop Project
observed (-) charged oil drops could be kept from falling by charging electric plates and using an instrument that measures the charge of the drop
e- charge
1.59x10^-19 C
e- mass
Me = 9.11 x 10^-31 kg
Plum Pudding Model
thot (+) charge spread thru entire atom & expected heavy alpha particles would pass through the thin gold foil
Plum Pudding Debunked!?
Most alpha particles passed straight through, but some deflected at a large angle…rutherford concluded most of the mass was concentrated in a very small & dense (+) charged particles
Rutherford Model
nucleus posses net charge of +Ze, w/ Z electrons surrounding the nucleus
Particles w/ thier mass & charge
e-
p+
N
Charge & Mass:
e- = (1-) = 9.11 x 10^-31 kg
p+ = (1+) = 1.67 x 10^-27 kg
N = (None) = 1.67x10-27 kg
Atom structure
tiny nucleus surrounded by electron cloud (without neutrons, protons wouldn’t stick together)
baseball size nucleus = _____ diameter
pea size nucleus weighs _______ tons
4 km
250 million tons
Harold Clayton Ureg discovery, where, & how?
deutrium & won noble prize for it, found in HAVEMEYER, 5L liquid hydrogen distilled to 1mL using distillation apparatus (went from 1st to 2nd floor) then let evaporated liquid condense at room temp. then measured spectrum of light emitted by passing a high xxx
- also lead isotope separation studies
Nuclide characterized by
p+ (Z) or atomic #
# neutrons (N)
mass # (Z + N = A) or (# prontons + # neutrons)
Isotopes
Nuclides of same elements w/ diff. mass #’s (A)
- also means “same place”
- introduced by F. Soddy to explain observations on radioactivity
Isotopes of Hydrogen
protium: 1 p+ & 0 neutrons (99.985%)
deuterium: 1 p+ & 1 neutron (0.015%)
tritium: 1 p+ & 2 neutrons (radioactive w/ 1/2 life of 12.3 years)
Isotopes of Carbon
C12: 6 p+ & 6 neutrons (98.89%)
C13: 6 p+ & 7 neutrons (1.11%)
C14: 6 p+ & 8 neutrons (radioactive w/ half-life of 5,730 years)
Meaning of subscripts in a chemical formula
relative number of atoms present
Chemical Bonds
how atoms are connected together (very from compound to compound)
Covalent Bonding
sharing of elements to hold atoms in molecules together
“flat drawing”
indicates connectivity
in a perspective drawing
solid line =
dashed line =
wedged line =
solid line = bonds in the plane
dashed line = atom connected to central atom behind the plane
wedged line = atom connected to central atom is in front of the plane
Ionic Bonding
electrons are completely transferred from one atom to another, resulting in formation of charged atoms (ions)
How does Ionic bonding work?
attraction between cations (+ ions) & anions (- ions)
Isotropic
finds anything around them that isn’t oppositely charged
Non-directional bonds
Ionic…allows ionic solids (salts)
Periodic table
links together families of elements that have similar chemical or physical properties
- chemical & physical properties of the elements are periodic functions of the atomic # (# p+ = # e- in the neutral atoms…the later determines the chemistry)
Q: Why does carbon combine w/ 4 atoms of hydrogen to form CH4, wheras oxygen combines w/ only 2 atoms of hydrogen to form H20?
Q: Why does helium exist as atoms (He), wheras hydrogen exists as diatomic molecules?
A: concerned w/ electronic structures of the individual atoms & these are dictated by the positions of the elements in the periodic table
8 groups of main group elements
- Alkali metals: (H). Li, Na, K, Rb, Cs
- Alkaline earth metals: Be, Mg, Ca, Sr, Ba, Ra
- Boron family (teriels): B, Al, Ga, In, Tl
- Carbon family (tetrels): C, Si, Ge, Sn, Pb
- Nitrogen group (pnictogens): N, P, As, Sb, Bi
- Chaliogens: O, S, Se, Te, Po
- Halogens: F, Cl, Br, I, At
- Noble gasses: He, Ne, Ar, Kr, Xe, Rn
Alkali Metals
H, Li, Na, K, Rb, Cs
Alkaline Earth Metals
Be, Mg, Ca, Sr, Ba, Ra
Boron family (teriels)
B, Al, Ga, In, Tl
Carbon family (tetrels)
C, Si, Ge, Sn, Pb
Nitrogen group (pnictogens)
N, P, As, Sb, Bi
Chaliogens
O, S, Se, Te, Po
Halogens
F, Cl, Br, I, At
Tin & lead are metals butt react similar too ___________
Silicn
Mendeleev Periodic Table organization
Chemical & physical properties of the elements are periodic functions of their atomic masses
Bottom rows of elements
Lanthanides & Actinides
Do actinides occur naturally or artificially?
Mostly artificially, butt thorium & uranium have a reasonable natural occurrence
1-18 numbers on periodic table
1-9 indicate # of valence electrons and once in double digits, the 2nd number indicates the # of valence electrons
Core e-
aren’t normally available for bond forming
- exception is group 11 (Cu, Ag, & Au which may have valence of 1, 2, or 3)
Characteristics of Metals
- Metallic luster (shine)
- Good conductor of heat & electricity
- Malleable (hammered into sheets)
- Ductile (drawn into wire)
Characteristics of Non-metals
- dull color
- poor conductor of heat & electricity
- brittle
Semimetals/metalloids
have characteristics that resemble metals in some regards & nonmetals in others (form a zigzag line of division)
metalic or nonmetalic
left side periodic table =
right of periodic table =
left = metalic
right = non metalic
lighter element examples =
heavier elements examples =
N2, O2, Fe
Bi, Te, I2
Most abundant element in the universe
Hydrogen
Lightest element
Hydrogen
2nd lightest element that doesn’t burn
Helium
2nd most abundant element in the universe
Helium
Element used in cryogenics & MRI
Helium
Combine w/ water to give alkaline solutions
Alkali Metals (G1)
Soft metals that can be cut w/ a knife
Alkali Metals (G1)
Malleable & ductile metal (ex. sodium wire)
Alkali Metals (G1)
Highly reactive metals towards water liberating H2 that ignites of explodes
Alkali Metals (G1)
Alkali metal compounds
form compounds w/ M+ ions (ex. NaCl)
- Na burns in Cl2
Meaning of “Earth” in Alkali Earth Metals
substances that are insoluble in water & stable to heat (originally referred to oxides of these elements)
Harder than Alkali metals
Alkali earth metals
Alkaline Earth Metal Info
- less reactive than alkali metals
- usually forms compounds that features M2+ ions + 2e-
Organic Chemistry
Chemistry of carbon (will bond w/ all sorts of elements & structure)
Meaning of carbon existing allotropy
existence of 2+ structural forms of an elements in the same states
ex. diamond, graphite, fullereness
Group that transition from non-metalic (C) to semimetalic (Si, Ge) to metalic (Sn, Pb) character
Carbon group
Fullerenes
C60 is a soccer ball made of hexagons & pentagons
Diamond info
- hardest known naturally occurring substance
- only made under high temp. & pressure where its thermodynamilly more stable
Is diamond or graphite more stable @ room temp & pressure?
Diamond is thermodynamically unstable w/ respect to graphite, but is kinetically stable
Carbon Nanotubule
Different roles influence electric conductivity
Graphite
flakes easily but more stable then diamond
Endohedral Fullerenes
Most expensive material in the wrld $167,000,000/g
Silicon for Electric Industry
Singte, pure, silicon crystals (cut into wafers & used in computers)
Carbon Group Compounds
Form tetravalent compounds of composition MX4, but tin & lead also form divalent 1:2 compounds (the inert pair effect)
2 coordinate divalent
stable for tin & lead butt highly reactive speicies for carbon
Petroleum Fuels
hydrocarbon
ex. octane
Carbon Dioxide
- formed when something burns or we breathe
- responsible for “greenhouse effect”
- increasing levels makes rivers, lakes, & oceans acidic & kill certain plants & animals
Dry Ice
goes from solid to gas (sublimation)(made of CO2)
Nitrogen
- main component of air (80%) & oxygen is (20%)
- gas but becomes a liquid @ very low temperatures
- used in MRIs & coding
Nitrogen compounds
- ammonia & nitric acid are 2 of the most nitrogen compounds made on a massive scale
- nitric acid used for dyes, drugs, fertilizers, & explosives
Phosphorus
- matches are a mix of red phosphorus & potassium chloride
- lots of allotropes
Bismuth
true structure isn’t known & is in pepto bismol
Chalcogen meaning
ore former (ex. metal oxides & sulfides)
Chalcogens
- transition from nonmetallic (O, S, Se) to semimetallic (Te, Po)
- Po is reactive and little studied
Combustion of metals in O2
- metlass react w/ O2 to form oxides
- iron reacts slowly w/ O2 in the presence of water @ room temp. to give rust & oxide-hydroxides
- iron burns readily in O2 to give ultimately Fe2O3
Water
- burn hydrogen & oxygen
- in one molecule of water, 3 atoms are bonded together
H2O & H2O2 is an example of
Law of Multiple Proportions
Hydrogen Peroxide
- 2 atoms of hydrogen & 2 atoms of oxygen
- unstable & decomposses to water & oxygen
- often used as bleach
Halogens Greek
Halos = salt
Genes = forming
Group that only exists as diatomic molecules & are nonmetals
Halogens (F, Cl, Br, I, At)
Melting point on periodic table
Increases further right you go
Inert/Noble Gasses
He, Ne, Ar, Kr, Xe, Rn
Group where compounds exist in a monoatomic form relative to a certian degree
Inter/Noble Gases
1st noble gas compound
Xe + PtF6
Mass Spectrometer
measures atomic & molecular mass
How Spectrometer works?
- Ionizing sample w/ e- bombardment (removing or adding e-)
- Accelerating ions thru a magnetic field
- Measuring amount of deflation (depends on mass/charge ratio)
- smallest ions on top & biggest on bottom of detector plate
Atomic Masses
mass of individual atom or deflected more
- reported relative to mass of C12 being defined as 12 atomic mass units
C12 weight
12.01 amu
How does carbon naturally exist?
mixture of isotopes C12 & C13
Ratios of Reactants
2 bread slices + 1 cheese = cheese sandwich
soooo 2H2 + O2 –> 2H2O (2 molecules of H2 react w/ 1 molecules of O2 to give 2 molecules of H20)
- use atomic mass to calc. ratio
Avagadro’s Number
of atoms in 12g of C12
6.022x10^23
universal constant
Mole
unit that corresponds to Avogadro’s # of particles
Na x volume of 1 molecule =
volume occupied by molecular mass in grams
How is volume of 1 molecule determined?
X-Ray
How is molecular mass in grams determined?
Density
mass (g) of any element is numerically equal to
relative atomic mass of that element
