CHEM 1110: General Chemistry Test 1
70 Cards in this Set
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Atoms
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Smallest portion of an element that still retains the characteristics of that element
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Molecules
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Two or more atoms joined chemically in a specific geometrical arrangement
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Scientific Law
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A brief statement or equation that summarizes past observations and predicts future ones
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What is the law of. conservation of mass
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Scientific law states that matter can neither be created or destroyed
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Theory
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A proposed explanation for observations and laws based on well-established and tested hypotheses, that presents a model of the way nature works and predicts behavior beyond the observations and laws on which it was based
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Scientific method
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A way of learning that emphasizes observation and experimentation to produce knowledge as the result of the senses
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Matter
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Anything that takes up space and has mass
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Substance
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A single kind of matter that always has a specific makeup--or composition--and a specific set of properties.
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Crystalline
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Solids in which atoms or molecules that composed themselves are in a WELL ORDERED three demensional array
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Mixture
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A physical combination of two or more pure substances in which each substance retains its own chemical identity
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Element
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Substance that cannot be broken down to other substances by chemical reactions (92 naturally occurring, 25 essential to life)
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Compound
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Substance that is made up of 2 or more elements in a fixed, definite proportion
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Heterogeneous Mixture
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A mixture in which the particles of a substance are not evenly distributed
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Homogeneous Mixture
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A uniform mixture of particles of different substances that form a single phase; also called solution
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Physical Change
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A change in matter from one form to another that doesn't result in a different substance
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Chemical Change
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A change in the identity of a material that results in a different material with a different composition and properties
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Physical Property
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Observed and measured without changing identity of substance
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Chemical Property
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Any property of a substance that cannot be studied without converting to substance into some other substance.
ex. burning
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Amorphous
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A type of solid matter in which atoms or molecules do not have long-range order (ex: glass and plastic).
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Law of Definite Proportions
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All sample of given compound, regardless of source or how prepared, have same proportions of constituent elements. (Proust)
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Law of Multiple Proportions
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When two elements from a series of compounds, the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers (Dalton)
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Atomic Theory
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All matter is composed of extremely small particles called atoms.
All atoms of a given element are alike, but atoms of a given element differ from the atoms of any other element.
Compounds form when atoms of different elements combine in fixed proportions.
A chemical reaction involves …
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Electrical Charge
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Fundamental property of protons and electrons-positive->positive or negative to negative charges repel
Opposite attract
Positive and negative cancel each other out so that a proton and electron when paired are neutral
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Electron
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Negative charge
Participates in chemical reactions
Outer-shell determine chemical behavior
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Radioactivity
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Fissure (break down) of a nucleus resulting in the release of particles and energy (radiation) and creation of a stable daughter atom
Alpha particles are positively charged and most massive of the three
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Nuclear Theory
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Most of an atom's mass and all of its (+) charges are contained in a small core called the nucleus.
Most of the volume of the atom is empty space, throughout which tiny, negatively charged electrons are dispersed.
Many negatively charged electrons outside the nucleus as there are positi…
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Atomic Mass Unit/Atomic Mass
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Mass exactly equal to 1/12 the mass of 1 carbon-12 atom
Mass of an atom in atomic mass units
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Atomic Number
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The number of protons in the nucleus of an atom of an element and its isotopes, used to determine that element's position in the periodic table
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Natural Abundance
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The percentage of a particular isotope of an atom found in a natural sample of that element.
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Isotopes
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The different isotopes of an element have the same number of protons and behave identically in chemical reactions, but they have different numbers of neutrons.
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Ions
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Charged atoms because of the unequal number of protons and electrons
An atom that looses one or more electrons becomes a positively charged particle, or ion.
An atom that gains one or more electrons becomes a negative charged particle or ion.
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Cation vs. Anion
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cation is a ion with a plus charge
ation is an ion with a negative charge
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Periodic Law
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When elements are arranged in order of increasing mass, certain sets of properties occur periodically
(Mendeleev)
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Metals/Nonmetals Location
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Metals: left side of the stairs
Nonmetals: Right side of the stairs (gases)
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What are Metalloids?
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Metalloids have properties of both metals and nonmetals.
Some of the metalloids, such as silicon and germanium (metal), are semi-conductors. Can carry an electrical charge under special conditions
Makes metalloids useful in computers and calculators
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Physical/Chemical Properties of Alkali metals, Alkaline Earth metals, Halogens and Noble Gases
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Alkali metals: soft, shiny metals; readily react with H20
Alkaline earth metals: soft, shiny metals; react moderately with water
Halogens: reactive, colored elements; F2 and Cl2 are gases at room temp
Noble gases: unreactive gases; undergo few chemical reactions
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Atomic Mass
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It is approximately equivalent to the number of protons and neutrons in the atom (the mass number) or to the average number allowing for the relative abundances of different isotopes
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Mole (def.)
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6.0221421 x 1023 Particles
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Molar Mass (def.)
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The mass of 1 mol of any substance, in units of grams per mole
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Why is Avogadro's Number not a simpler number?
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Number is equal to the number of of atoms in exactly 12g of C
amu is also defined to the relative to Carbon-12 Therefore, the mass in grams of 1 mole = to it's atomic mass
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How do you find # of protons, electrons, and neutrons element?
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Protons = Atomic #
Electrons = Atomic # (unless the atom is not neutral, then look at the charge)
Neutrons = Isotope - Atomic #
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True or False: Elements in the same group are likely too have the same chemical & physical properties.
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True
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1 mol Equals How Many atoms?
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6.022 x 1023 (Avogadro Number)
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If matter is homogeneous and a pure substance and it can be separated into simpler substances, what is it?
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Compound
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Ions are formed when an atom _____
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An electrically charged atom or group of atoms formed by the loss/gain of one or more electrons**
none of these
gains/loses protons or gains/loses neutrons
shares electrons w/ another atom
shares protons w/ another atom
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Electromagnetic Radiation
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Series of "waves" having different wavelengths
Wavelengths are inversely proportional to frequency
All objects at a temperature above absolute zero emit electromagnetic radiation
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Frequency, Wavelength and Amplitude
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Frequency = number of waves per second
Amplitude = from undisturbed point to most disturbed point in a straight vertical line
Wavelength = from the normal up then down to the trough
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How does an atom emit light?
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1. A charged particle hits an electron
2. The atom is in it's excited state and the electron jumps to a higher orbit
3. The electron returns to it's origional orbit and releases the gained energy and a light photon is produced
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Quantum Mechanical Model
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Electrons exist in regions of space called orbitals
BUT the electron's exact place can never be known
Orbitals are represented as dense clouds and less dense clouds to show regions where electrons are likely to be
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Orbital
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Represented by Ψ2;
The space around the nucleus in an atom where an e- is likely to be found
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Quantum Numbers (def.)
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The numbers evolve from the Schrödinger equation and characterize the various solutions to it
n = distance of an electron from the nucleus
l = the shape
ml = orientation
ms = spin
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Electron Configuration
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Ways in which electrons are arranged around the nuclei of atoms
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What is the difference between an electron configuration and an orbital diagram?
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An orbital diagram gives more info by showing the spins on electrons and how each energy level is filled, electron configs simply tell us the number of electrons per shell
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Core/Valence Electrons
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electrons in fully filled shells are called core electrons
electrons in the shell with the highest principal quantum number (outermost shell) are called valence electrons
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Significance of Valence Electrons & Chemical Properties
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valence electrons are responsible for chemical properties of and element
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Valence Shell/Valence Electrons
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The outermost shell of electrons is called the valence shell.
Electrons in the outermost (valence) shell are called valence electrons.
They are distinguished from core electrons and shells because the valence shell/electrons of an atom interact with each other
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Groups (Columns) and Names
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Vertical columns of the periodic table; (18) elements have similar properties
Group I = alkali metals
Group II = alkaline earth metals
Group XVII = halogens
Group XVIII = noble gases
Group 3-12 Transitional
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What are the vertical elements called on the periodic table? Horizontal?
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Periods/rows/series are vertical
Columns/Groups/Families are horizontal
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What is the concept of a mole and amu's?
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1 amu = 1.661 x 10^-24 grams
1 mole = 6.022 x 10^23
grams to moles to atoms
1 mole = atomic mass
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Calculate atoms in a mole of Cu
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6.022*1023 Atoms
6.022 x 1023 Atoms = 1 Mole
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3.10 g Cu
Find # of Cu atoms
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3.10g x [(1 mol Cu/63.55g)] x [(6.022 x 1023 Cu atoms/1 mol Cu)]
=2.94 x 1022 Cu atoms
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7 diatomic elements
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Hydrogen (H2)
Nitrogen (N2)
Oxygen (O2)
Fluorine (F2)
Chlorine (Cl2)
Iodine (I2)
Bromine (Br2)
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How can mixtures be separated?
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By the differences in their physical properties
Particle size - filtering
Magnetic substances - use of a magnet
Boiling point - evaporation
Density - use of a centrifuge
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Atomic emission
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Pattern formed when light passes through a prism or diffraction grating to separate it into the different frequencies of light it contains.
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Phosphorescence
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The persistent emission of light following exposure to and removal of a source of radiation
A phosphorescent source of light is similar to a fluorescent source.Light energy is absorbed by certain particles that store this energy. Stored energy is later released as visible light. The orig…
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Fluorescence
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Pathway of excited atom/molecule when it returns to ground state
Emission of Energy
Excited singlet state to singlet ground state
Quicker
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Trends for Atomic Radius?
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Atomic Radius increases down a group due to the increased number of shells, which increases shielding.
Decreases as you move along a period due to the increased nuclear charge of the elements.
Shielding
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Reactivity Trends (metals)
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Across a period - decreases
Radius gets smaller , electrons are closer to the nucleus making it harder to remove an electron
Down a group - increases
Radius increases, electrons are farther from the nucleus so they feel less attraction makes easier to remove an electron
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Reactivity Trends (nonmetals)
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Get more reactive going up and to the right
Fluorine is the most reactive
Noble gases don't react!
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Common Unit Conversions
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1 kg=1000 g
1 g=10 dg
1 g=100 cg
1 g= 1000 mg
1 g= 106 micrograms
1 g= 109 nanograms
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CHEM 1110: General Chemistry Test 1