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39 Cards in this Set
- Front
- Back
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matter
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anything that takes up space and has mass
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element
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a substance that cannot be broken down to other substances by chemical reactions-pure
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compound
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a substance consisting of two or more different elements combined in a fixed ratio
EX: table salt, NaCl, ration 1:1 of Na and Cl |
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elements of life
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25 of the 92 natural elements that are known to be essential to life
EX: carbon (most important), oxygen, hydrogen, nitrogen make up 96% of living matter. Others include: phosphorus, calcium, sulfer, potassium, etc... |
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trace elements
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elements required by an organism in only minute quantities.
EX: iron |
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atom
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the smallest unit of matter that still retains the properties of an element
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subatomic particles
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neutrons, protons, and electrons
Neutrons and protons are packed together to form the atomic nucleus (center of atom), while electrons, moving at the speed of light, from a cloud around the nucleus. |
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electrons
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subatomic particles circling the atomic nucleus
They are electrically charged, so depending on placement and number, an element may be positively, negatively charged, or neutral. |
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dalton
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unit of measurement for subatomic particles, in honor of John Dalton who developed the atomic theory
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atomic number
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the number of protons
is unique to each element is written as a subscript to the left of the symbol for the element |
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mass number
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the sum of the protons plus the neutrons in the nucleus in the nucleus of an atom
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atomic mass
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the mass of the atom
mostly concentrated in the nucleus |
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isotope
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different atomic forms of the same element
some atoms have more neutrons in their nucleus than other atoms of the same elements, changing their atomic mass |
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radioactive isotope
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an isotope in which the nucleus decays spontaneously, giving off particles and energy
changes in the number of protons of that atom lead it to change to a different element EX: a radioactive carbon decays to form nitrogen |
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energy
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is defined by the capacity to cause change, for an instance by doing work
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potential energy
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the energy that matter possesses because of its location or structure
EX: b/c of its altitude, water in a reservoir has potential energy. |
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energy levels
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the different states of potential energy that electrons have in an atom
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electron shells
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distance of electrons from nucleus; farther shell means a higher energy level
EX: light energy can excite the electrons so that they change their energy level. They'll jump from the original level and then fall back. |
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valence electrons
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the electrons in the outermost shell of the atom
most of the chemical behavior of an atom depends on how many are there |
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valence shell
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the outermost shell of electrons
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electron configuration
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first shell: max 2 electrons
2nd and on: 8 max must fill previous shell completely before moving on to the next |
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orbital
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the three-dimensional space where an electron is found at 90% of the time
no more than 2 electrons can occupy a single orbital |
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chemical bonds
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attractions that holds atoms together
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covalent bond
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the sharing of a pair of valence electrons by two atoms
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molecule
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two or more atoms held together by a covalent bond
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single bond
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a pair of shared electrons
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structural formula
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a representation of atoms that have bonded using lines for bonds and the elements symbol
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molecular formula
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abbreviations of the bond
EX: H2 |
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double bond
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the sharing of two pairs of electrons
a double covalent bond |
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valence
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an atoms bonding capacity
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electronevativity
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the attraction of a particular kind of atom for the electrons of a covalent bond
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nonpolar covalent bond
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a bond in which the electrons are shared equally
"In a covalent bond between two atoms of the same element, the outcome of the tug of war for common electrons is a standoff; the two atoms are equally electronegative." |
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polar covalent bond
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a bond where one atom is bonded to a more electronegative atom
the electrons are not shared equally EX: the water molecule |
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ion
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a charged atom or molecule
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cation
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a positively charged ion
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anion
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a negatively charged ion
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ionic bond
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a bond where two oppositely charged ions come together and their charges cancel out
EX: +1Na and -1Cl = NaCl |
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ionic compounds (salts)
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compounds formed by ionic bonds
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hydrogen bond
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forms when a hydrogen atom covalently bonds to one electronegative atom and is also attracted to another electronegative atom
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