the study of the composition, structure, and properties of matter, the process that matter undergoes, and the energy changes that accompany these processes.
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chemical
a compound or substance that has been purified or prepared
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mass
the measure of the amount of matter in an object
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matter
anything that has mass and takes up space
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atom
smallest unit of an element that maintains the chemical identity of that element
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molecule
smallest unit of a compound that retains the same properties of a compound
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element
a pure substance that cannot be broken down into simpler, stable substances
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compound
a pure substance that can be broken down into simple substances, made of more than one element
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extensive property
depends on the amount of matter that is present. ex. volume, mass, or amount of energy in a substance
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intensive property
does not depend on the amount of matter present. ex. boiling, melting, density, or the ability to conduct heat or electricity
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physical properties
something we can observe and measure without changing the identity of the substance. ex. finding melting or boiling point, density
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chemical properties
substance’s ability to undergo changes that transform it into different substances. ex. flammability, toxicity, acidity, reactivity
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change of state
the change of a substance from one physical state to another
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plasma
high-temperature physical state where atoms lose most of their electrons
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mixture
a blend of two or more kinds of matter, each of which retains its own identity and properties
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physical change
a change in a substance that does not involve a change in the identity of the substance. ex. grinding, cutting, melting, boiling
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chemical change
a change in which one or more substances are converted into different substances. clues to this are color change, precipitation, and gas. ex. burn, corrode, rust, explode
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AMU
atomic mass unit
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conservation of mass
mass cannot be created or destroyed
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Law of Definite Proportions
chemical compound always has fixed ratio by mass
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Law of Multiple Proportions
when 2 elements combine, their ratio is in whole numbers
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mole
6\.02 x 10^ 23. unit for very small things in very large numbers
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molar mass
mass of one mol of a substance, ex. 6 g/mol
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isotope
atoms with the same number of protons but different numbers of neutrons
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empirical formula
most basic ratio of elements in a compound
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molecular formula
true ration of elements in a compound, unsimplified
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ion
an atom in which # of electrons is not equal to the # of protons
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anion
negatively charged ion
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cation
positively charged ion
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isoelectric
same charge
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Democritus
Proposed that the world is made of tiny particles. Was the first person to come up with the idea of an atom
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Aristotle
Believed matter was made up of five elements
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John Dalton
English scientist who developed an atomic theory with five main postulates. Also the first to discover the properties of an atom
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JJ Thomson
English scientist who discovered the electron using a cathode-ray tube, “Plum Pudding” Model
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Robert A. Milikan
Determined the charge of an electron using the oil drop experiment
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Ernest Rutherford
Discovered protons and the nucleus of an atom using the gold foil experiment. Also discovered that atoms are mostly empty space
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Niels Bohr
His atomic model shows electrons in distinct energy levels, electron configuration
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James Chadwick
Discovered the neutron, led to the atomic bomb
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Frederick Soddy
Discovered the isotopes of elements
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Henry Moseley
Linked the atomic number to the number of protons in the nucleus and that protons have a positive charge
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Antoine Lavoisier
Father of modern chemistry, made it more quantitative as opposed to qualitative
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Robert Bunsen
Invented the Bunsen burner, techniques in data collection with compounds and elements
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Bohr Diagram
circular diagram showing electrons
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Aufbau Principle
fill in lowest available energy level first
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Pauli Exclusion Principle
Each orbital can hold a max of 2 electrons
Electrons must spin in opposite directions
Arrows represent electrons
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Hund’s Rule
Spread out electrons within an energy sublevel before pairing them up
one-half the distance between the nuclei of identical atoms that are bonded together. increases to the bottom and left
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electronegativity
the tendency of an atom or a functional group to attract electrons towards itself. increases up and right
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ionization energy
the amount of energy required to remove an electron from an isolated atom or molecule. increases up and right
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electron affinity
the amount of energy released when an electron attaches to a neutral atom to form a negatively charged ion. increases up and right
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period
The horizontal rows of chemical elements on the periodic table. Every element in a period have the same number of electron shells
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group/family
The vertical columns of chemical elements on the periodic table. Each element in a group/family has the same number of valence electrons and have similar chemical and physical properties
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precision
repeatable and reliable
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accuracy
a correct measurement
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homogeneous mixture
composition is uniform throughout, can’t be pulled apart. ex. juice, glue, milk
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heterogenous mixture
composition is not uniform, can be pulled apart. ex. salad, chicken soup, sandwich
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how to read a caliper
Line up jaws, keep big number, first aligning small number is decimal
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Steps for scientific method
Observation, hypothesis, experiment, data analysis, conclusion (OH EDAC)
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metals
good conductors for heat and electricity
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nonmetals
poor conductors for heat and electricity
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noble gases
inert, very stable, don’t form compounds
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halogens
non-metals, strong odor, don’t dissolve well, react with most non-metals and metals
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alkali metals
1 valence electron, very reactive, soft, stored under oil. form cations
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alkaline earth metals
2 valence electrons, not as soft or reactive as alkali metals. form cations
Studied by 22 people
