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Chap. 17/18
Physical Science
Term | Definition |
---|---|
element | any pure substance that is made of only one kind of atom |
How did the Ancient Greeks first define the elements? | As the basic building blocks of matter |
Aristotle believed in 4 "elements" | AIR, FIRE, EARTH, WATER |
Alchemy | aspects of chemistry, philosophy, religion, metallurgy, medicine, and art. |
Alchemy became a real science when? | in the 17th & 18th centuries |
Isaac Newton, Robert Boyle, & Antoine Lavoisier believed that | true scientific knowledge was gained by observing, experimenting, and reasoning |
How many elements are there today? | 117 |
The heaviest elements are all radioactive and have _____ ________ half lives so they are difficult to analyze | VERY SHORT |
How many naturally occurring elements are there? | 92 |
all but ____ are solids at room temperature in their pure forms | 13 |
___________ (__) & _______________ (___) are liquids | Mercury (Hg), Bromine (Br) |
remaining 11 are gases | Hydrogen (H), Helium (He), Nitrogen (N), Oxygen, Fluorine (F), Neon (Ne), Chlorine (Cl), Argon (Ar), Krypton (Kr), Xenon (Xe), and Radon (Rn) |
Monotomic elements: | have 1 atom in natural state |
Diatomic elements (definition) | have 2 atoms in their natural state |
diatomic elements | Hydrogen2, Nitrogen2, Oxygen2, Florine2, Chlorine2, Bromine2, Iodine2 |
19th century: Dmitri Mendeleev arranged the --- | elements into what eventually became the periodic table used today |
Johan Dobereiner, placed elements in order of ________________ _____ | increasing, mass |
With his, almost all the groups contained 3 elements called ________ | TRIADS |
His idea was important because as new elements became better understood, | chemists started to recognize patterns in properties |
Periodicity | the repetition of certain properties at regular intervals when elements were placed in order of atomic MASS |
John Newlands | arranged the elements in the table in order of their increasing atomic masses. |
when arranged in 7 columns he noted that in most cases every 8th element had similar properties | OCTAVES |
When Mendeleev organized the elements he had an important feature | BLANK SPOTS= spots for undiscovered elements |
Mendeleev called the principle that the properties of elements vary in a periodic or recurring pattern with their atomic masses | Periodic law |
Who arranged the elements in order of increasing atomic number? | Henry Mosely |
Revised periodic law | the properties of the elements vary with their atomic number in a periodic way |
Metals | belong to families w/ relatively few valence electrons, These valence electrons aren't held very strongly & are easily removed. If it weren't for the "loose" electrons, metals would have a metallic luster, be malleable, ductile, or conduct electricity. |
Metals on the periodic table | alkali metals (1A), alkaline earth metals (2A), transition metals (middle part), inner transition metals (7A), metals to the right of the "staircase" |
Non-Metals | hold their electrons tightly, so their properties are very different from metals. They lack luster, are brittle (opposite of malleable), don't conduct electricity, and are NOT ductile. |
PERIODS | the horizontal rows of the periodic table. Tells how many MAIN ENERGY LEVELS the elements in that period have in their GROUND STATE |
ground state | the lowest energy state for the electrons |
the number of _________ ___________ | is important in determining the chemical & many physical properties of the element |
the MORE energy levels an atom has, the _________ it is | LARGER |
The larger it is, the _________ the valence electrons are from the nucleus. Thus the ______________ of the nucleus on the valence electrons is ___________ | farther, ATTRACTION, WEAKER |
less protons & electrons weaker for it to hold atom= | looser, larger |
more protons & electrons, stronger to hold atom= | tighter, smaller |
when the element has the same energy levels as another, look at the _______ ___________ to tell which on is bigger | atomic number (proton count) |
The tendency for atoms to from bonds is governed by the- | SECOND LAW OF THERMODYNAMICS |
The second law of thermodynamics states | all natural processes move toward a state of minimum energy |
Octet rule | Atoms generally are most stable when they have 8 electrons in their valence energy level. Some exceptions are H (1 electron, 1 energy level that holds only 2 electrons max) and the next 3 elements, Li, Be, B. |
Atoms can ______ , ______ , or ______ electrons to get to the octet | gain, lose, share |
When atoms gain & lose electrons they make _____ | IONS- have charges, then the opposite charges are attracted to each other |
Cations | positive |
Electron affinity | deals with the strength of attraction of electrons to UNBONDED ATOMS. |
Atoms with high electron affinities will _____ or _____ electrons from other atoms. | take, share |
Atoms with low electron affinities will _____ their valence electrons or have a very small part in sharing them when bonding | lose |
Electronegativity | deals with an atom's ability to attract & hold electrons when BONDED TO OTHER ATOMS. |
The more electronegative the more likely it will _____ electrons | take |
factors of electronegativity | energy levels, valence electrons |
non-metal/non-metal-shares electrons | COVALENT BONDS |
metal/non-metal-giving away and taking electrons | IONIC BONDS |
ionic bond | bond, ionic bond, taken, not shared |
metal/metal-everyone shares the electrons (de-localized, "electron socialism" | METALLIC BONDS |
*Electron Sea theory* | Atoms with weak electronegativities usually have only a few loosely held valence electrons. These atoms bond by sharing their easily lost electrons among many atoms. These mobile electrons are not associated with any specific nucleus. |
Fluorine (F) | highest electronegativity (-) |
Francium (Fr) | least electronegative |
ionic bonds _________ _____________ | conduct electricity |
covalent bonds melts at ________ temperatures that ionic bonds | lower |