Question Answer
Atom the smallest piece of an element
Proton particle in the nucleus of an atom with a positive charge
Neutron particle in the nucleus of an atom that does not have a charge
Electron particle found outside of the nucleus (shell/cloud) and has a negative charge
Atomic Number the number of protons in an atom (also electrons)
Isotopes atoms of the same element such as hydrogen but with different numbers of neutrons
Mass Number the number of both protons and neutrons in an atom
Periodic Table a way of organizing all of the elements found in the universe
Periods horizontal rows on the Periodic Table (The period number is the number of shells)
Groups/Families vertical columns on the Periodic Table where elements have similar chemical properties.
Valence Electrons the number of outer electrons in an atom. (It is the Group Number for the Main Elements) 1/2/3b…8b
Metals elements on the LEFT side of the Periodic Table that are usually soft/shiny/malleable/ductile/low specific heat/high melting points/good conductors
Non-metals elements on the RIGHT side of the Periodic table that are usually dull
Transition Metals elements in the middle of the Periodic Table
Metalloids elements along the zig zag stair case that have properties of both metals and nonmetals
Element a substance made up of only one atom
Compound a substance made up of two or more elements that have been chemically combined
Mixture two or more substances brought together but are not combined chemically and still keep their same properties
Matter anything that has mass and takes up space
States of Matter solid/liquid/gas/plasma
Solid has a definite shape and definite volume
Liquid has a definite volume but not a definite shape
Gas has a definite volume but not a definite shape
Plasma a gas at high temperatures where it has become electrically charged (lightning/fluorescent lights/Auroras/stars)
Physical Changes a change where the material keeps it's same properties such as tearing
Evaporation physical change where a liquid becomes a gas (usually due to increasing temperature)
Condensation physical change where a gas becomes a liquid (usually due to cooler temperatures)
Chemical Changes change where a substance is changed into a new substance with new properties after a chemical reaction
Physical Properties properties that describe the appearance of a substance such as color/shape/texture/luster/melting point/mass/density/etc.
Texture the surface features of a substance (smooth/rough) Physical Property
Luster describes how a substance reflects light (shiny/metallic/dull)
Physical Property describes the appearance of a material
Ductile physical property of metals being pulled or stretched into wire without breaking
Malleable physical property of metals being hammered into sheets or bent into different shapes without breaking
Mass the amount of matter in an object (measured with a balance) (unit is gram) Does not change
Volume the amount of space an object takes up (measured with graduated cylinder or ruler) (units are ml or cm3)
Density the measure of how squeezed together particles are in an object ( units are g/ml or g/cm3)
Melting Point the temperature at which a solid changes to a liquid
Boiling Point the temperature at which a liquid changes to a gas
Chemical Properties properties that describe how a substance will react chemically with another substance
Flammability the ease atwhich a material will burn
Corrosive the ability of a substance to destroy another substance through a chemical reaction (acids corrode metals)
Reactivity the degree that a substance will react chemically
Toxicity the degree that a substance can damage an organism
Subscript the number written below an element that indicates the number of atoms present (example H2O)
Coefficient the number written in front of a formula that indicates the number of molecules that are present (example 3HCl)
Law of Conservation of Mass the mass of the reactants will be the same as the mass of the products. Matter is not created or destroyed.
Reactants the substances on the left side of an equation involved in the reaction
Products the substances on the right hand side of an equation that are formed in a reaction
Exothermic a reaction where heat is released ( the beaker gets hot)
Endothermic a reaction where heat is absorbed (the beaker gets cold)
Chemical Bond the force of attraction that holds atoms together in compounds or molecules
Signs of a Chemical Reaction color change/new odor/bubbling/temperature change/solid precipitate
Hypothesis a testable explanation or prediction
Conclusion summarizing the data and results of an experiment and either accepting or rejecting the hypothesis
Independent Variable the variable that we change to see the effect it will have on the dependent variable (example: amount of water )
Dependent Variable the variable that we are studying to see how it is affected by a change in some other variable (example:height of plants)
Controlled Variables variables that are kept constant so that the changes that we observe are only due to the independent variable that we change
Data the observations made in an experiment
Model a simple or abstract way of representing something. Example: used to describe atoms
Topographic Map a map that shows the surface features or elevation of an area
Mass the measure of the amount of matter in an object. (Instrument-balance) (Unit is grams) ( NEVER CHANGES)
Volume the measure of the amount of space an object takes up. (Instrument-graduated cylinder or ruler) (unit is ml or cm3)
Density the amount of matter squeezed into a certain space. (unit- g/ml or g/cm3). Physical Property
Buoyancy The upward force exerted on an object that is placed in a fluid
Archimedes Principle The buoyancy force is equal to the weight of water that is displaced by the object
Pure Substance An element or compound.
Mixture Two or more substances that are brought together but do not combine chemically.
Homogeneous mixture A mixture that has the same composition throughout ( example: salt water)
Heterogeneous mixture A mixture that does not have the same composition throughout. ( example: salad, pizza)
sublimation A change in state from a solid straight to a gas ( example- dry ice )
polar the uneven arrangement of electrons in a molecule ( one end is slightly positive, one negative)
adhesion The tendency of a material to stick to another material ( water-glass )
cohesion The tendency of molecules to be slightly attracted to each other (water beading up)
Ionic bond A bond that results from the gaining or losing of electrons ( metals-nonmetals)
Covalent bond A bond that results from the sharing of electrons (nonmetals – nonmetals
Solubility A property that describes how much solute can be dissolved at a given temperature

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