elements
substances that cannot be broken down into simpler substances by chemical means
CHNOPS
an acronym representing the 6 key elements of
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carbon
key element of life; major component of ALL organic compounds, including all 4 types of macromolecules (sugars, fats, proteins, and nucleic acids); rarely found unbound to other elements
hydrogen
key element of life, highly involved in the creation of protein gradients that enable photosynthesis and respiration
nitrogen
key element of life, especially prevalent in proteins and nucleic acids; wastes based on excesses of this element must be excreted by organisms to prevent the accumulation of toxic ammonia in cells
oxygen
key element of life, involved in processes like oxidative phosphorylation and a major component of many organic compounds; exists in the atmosphere in molecular form, small enough to permeate most membranes by simple diffusion
phosphorous
key element of life; especially important for its role in phosphate and thus in ATP molecules, which store energy to fuel the majority of cellular work
sulfur
key element of life; especially important in proteins, where disulfide bridges composed of this element help anchor peptide chains into functional shapes (tertiary structure)
trace elements
elements that are required by organisms in only very small quantities, such as Fe, Cu, I, etc
atom
the smallest unit of an element that retains its characteristic properties; composed of subatomic particles such as protons, neutrons, and electrons
nucleus
the center core of an atom where the protons and neutrons are concentrated
protons
positively charged subatomic particles located in the nucleus of an atom; constant for all atoms of the same element
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neutrons
subatomic particles that carry no charge; located in the nucleus of an atom; number can vary among atoms of the same element, leading to various isotopes (some of which are unstable, or radioactive, and spontaneously split due to instability)
isotopes
atoms of the same element that have different numbers of neutrons and thus different atomic masses; some are unstable, or radioactive
electrons
negatively charged subatomic particles that orbit the nucleus of an atom in a region of space called the "electron cloud"
valence electrons
the electrons of the outermost energy level of an atom that determine bonding characteristics
valence
the maximum number of bonds that an atom of a particular element can form; based on the number of valence electrons (8 - ve)
atomic number
the number of protons in all atoms of a specific element
mass number
the weighted average of the masses of the different isotopes of an element
atomic mass
the mass of an atom of a particular isotope of a particular element; equal to the number of protons plus the number of neutrons
compound
a combination of two or more different types of atoms in a fixed ratio
chemical reaction
the formation or destruction of chemical bonds between two or more atoms or compounds
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chemical bond
forces that hold the atoms of a compound together, including ionic bonds, covalent bonds, hydrogen bonds, etc
ionic bond
chemical bond formed when an electron is transferred from one atom to another, creating a positive ion and a negative ion, which are then attracted to one another by electromagnetic forces
formula unit
two or more ions (monoatomic or polyatomic) held together by ionic bonds
covalent bond
chemical bond formed when an electron pai [Show Less]