Basic Chemistry Flashcards
What is a compound?
atoms bonded together
What determines an atom’s identity?
number of protons (+)
matter
anything that takes up space or has mass
element
any substance consisting of two or more elements in a fixed ratio; it has its own emergent properties
essential elements
20-25 % of the 92 natural elements that are required for life
make up 96% of living matter
C, O, N, & H
4% of living matter
Ca, K, S, & P
trace elements
elements required by an organism in minute quantities
atom
smallest unit of matter that still retains the properties of an element
subatomic particles
neutrons, protons, electrons
Where are electrons found?
in a cloud of negative charge around the nucleus
What is found in the nucleus of an atom?
neutrons and protons
daltons
numerical value that is used for measurement of atom’s mass; protons and neutrons are considered
atomic number
number of protons in nucleus
mass number
sum of protons and neutrons in nucleus
atomic mass
atom’s total mass; can be approximated by the mass number; unit of measurement: amu
isotopes
two or more atoms of the same element that differ in number of neutrons
radioactive isotopes
isotopes that decay spontaneously , giving off particles and energy; have different masses and unstable nuclei that emit radiation
isomers
NOT ISOTOPES; compounds with the same formula but different arrangement of atoms
potential energy
energy that matter possesses because of its structure or location
energy
Capacity to cause change
electron shells
shells; each one with a characteristic average distance from the nucleus and energy level
valence electrons
electrons in an atom found in the outermost shell (valence shell)
atomic orbital
three-dimensional space where an electron is found 90% of the time; it describes wave-like behavior of an electron
