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Atom

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The smallest unit of an element that maintains the chemical properties of that element

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Element

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A substance that cannot be broken down into simpler substances by chemical means; all atoms of an element have the same atomic number

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Compound

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A substance made up of atoms of two or more different elements joined by chemical bonds; contains definite composition that can be broken down into simpler substances by chemical methods

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Physical property

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A characteristic of substance that doesn't involve a chemical change, such as density, color, or hardness

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Physical change

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A change of matter from one form to another without a change in chemical properties

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Change of state

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The change of a substance from one physical state to another

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Solid

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The state of matter in which the volume and shape of a substance are fixed; there is a strong attraction between the particles

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Liquid

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•The state of matter that has a definite volume but not a definite shape •particles constantly make and break temporary attractions b/t each other

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Gas

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•A form of matter that doesn't have a definite volume or shape •particles are independent, very far apart, with no attractive forces between them •fill total volume of a container

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Chemical property

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A property of matter that describes a substance's ability to participate in chemical reactions

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Chemical change/reaction

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The process by which one or more substances change to produce one or more different substances

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Reactants

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A substance or molecule that participates in a chemical reaction

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Products

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A substance that forms in a chemical reaction

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Mixture

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A combination of two or more substances that are not chemically combined

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Homogeneous

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Describes something with one phase that has uniform properties and a uniform structure or composition throughout

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Solutions

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A homogeneous mixture of two or more substances uniformly dispersed throughout a single phase

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Heterogeneous

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Mixtures with more than one phase and variable properties in different parts of the sample. Composed of dissimilar components

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Pure substance

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•composition is fixed or definite and always made up of the same elements in the same mass ratio •A sample of matter, either a single element or a single compound, that has definite chemical and physical properties

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Molecule

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The smallest unit of a substance that keeps all of the physical and chemical properties of that substance; it can consist of one atom or two or more atoms bonded together

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Alkali Metals

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A very reactive group- react violently w/ water They're all soft •low densities •low melting/boiling points

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Alkali earth metals

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•Highly reactive but not as reactive as group one, but are harder and have higher densities and melting points than group 1 •present in the earths crust but not in their basic form

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Halogens (nonmetal)

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•distinct color •low melting/ boiling point •very high electronegativities •highly reactive •can be harmful or lethal

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Noble gases

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•Unreactive- will not form compound- single atoms •colorless •very low chemical reactivity •little tendency to gain/lose electrons

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Metals (transition metals)

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•they form colored compounds •they are good conductors of heat/electricity •they can be hammered/bent to shape easily •they have high melting points/ density •Ductile & malleable •Shiny •Mostly solids

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Nonmetals

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•generally poor conductors of heat/electricity- insulators •solid non-metals are generally brittle with little to no metallic luster •gain electrons easily •non-malleable •usually liquid/gas •Low density/ melting/ boiling points •high ionization energies and electronegativities

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Metalloids

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Divide metals and nonmetals so they have properties of both

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The First International Congress of Chemists did what?

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Settled the issue of atomic mass

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Stanislao Cannizzaro

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Presented a convincing method for accurately measuring the mass of atoms allowing the chemists to agree on standard values for atomic mass

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Dmitri Mendeleev

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Created the periodic table

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Henry Mosely

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His work led to the modern definition of atomic number and recognized that the atomic number is the basis for the organization of the periodic table

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Periodic Law

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•the physical and chemical properties of the elements are periodic functions of their atomic number; {so when the elements are arranged in order of increasing atomic number, elements with similar properties appear at different intervals}

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Periodic Table

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An arrangement of the elements in order of their atomic numbers so that elements with similar properties fall into the same column/group

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John William Strutt {aka Lord Rayleigh} and Sir William Ramsay

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Discovered the gases Argon and Helium so Ramsay proposed a new group: noble gases

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In Dalton's Playhouse, during Priestly's experiment with the calx, what happened to the mass of the materials in the flask as it was heated?

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It decreased

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What did you note about the masses of the gas produced and the Mercury metal left in the flask?

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The mass of the gas was the same as the mass of the metal.

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What was the relationship between the volume of the gas produced and the mass of the calx that was heated?

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They were directly proportional; {as the volume went up so did the mass}

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In Lavoiser's experiment with the phlogiston, with relation to the volume of the gases, in what specific proportion did phlogiston react with oxygen?

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2 H: 1 O

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How did the mass of the gas in all three vessels before burning compare to the total mass after burning?

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They equalled each other because it was a closed system

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In the diamond and charcoal experiment, how did the mass of the gas formed compare if you used the same amount of diamond and charcoal?

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The masses of the gas were equal

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What is the core concept you can take away from experiment 1 with Priestly? And what law does it represent?

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Some substances are composed of discrete amounts of 2 or more other substances The Law of Definite Proportions

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What is the core concept you can take away from experiment 2 with Lavoisier? And what law does it represent?

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The total mass of the products in a chemical reaction is exactly equal to the mass of the reactants. The Law of Conservation of Mass

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What is the core concept you can take away from experiment 3 with the diamond? And what is the law it represents?

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Elements combine in specific, defined ratios in chemical reactions; Law of multiple (or definite) Proportions bc you had diamond and carbon

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Empedocles

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Proposed 1 of the first theories attempting to explain the things around us

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Democritus

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Came up with the idea of atomos (this mean indivisible) and developed new theory based on reasoning instead of science.

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Aristotle

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Believed Empedocles' theory adding his own incorrect idea that 4 elements could be transformed into each other

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Torricelli

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Invented the barometer saying air had mass, could exert force and could be measured

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Priestly

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Englishman who experimented with red calx and observed it broke down into 2 substances when heated: a gas and liquid Mercury. Theory: substances can break down and come together to form a different substance

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Lavoisier

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•Experimented dephlogisticated gas and proposed the theory that is made some some substances acidic renaming it oxygen •established the law of conservation of mass •discovered hydrogen burned with oxygen forms WATER

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Dalton

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Developed the 1st modern atomic theory

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Boyle

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•PRESSURE v.s. VOLUME law Discovered element was defined wrong and redefined it as a fundamental substance that cannot be broken down any further

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Proust

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•gave us the law of definite proportions •said compounds have defined chemical formulas

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Law of Definite Proportions

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•2 parts hydrogen + 1 part oxygen= water. •changing the proportions changes the substance

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What are the 4 main concepts of Dalton's Atomic Theory?

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•all matter is composed of indivisible particles called atoms •all atoms of a given element are identical; atoms of different elements have different proportions •chemical reactions consist of the combination of atoms not the destruction •when elements react to form compounds, they react in defined whole number ratios

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