Intro to chem part 1

​Matter

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• States of matter= solid (molecules don’t move), liquid (molecules move slowly), gas (molecules move rapidly)

Subject | Subject

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​Matter

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• Melting= molecules speed up (solid to liquid)

Boiling= molecules speed up (liquid to gas)​

• Freezing=molecules move slower (liquid to solid)

Condensation= molecules move slower (gas to liquid)

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Protons (p) have a positive charge

Neutrons do not have a charge​

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The nucleus of the atom contains the neutrons and protons.

The nucleus is surrounded by orbiting electrons.​

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• Atoms are the smallest unit of matter that make up elements. 

Atoms < Element< molecule< compound< mixture

​Elements- pure substances made of the SAME type of atoms that cannot be broken down any further.

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• Compound= atoms chemically combined

Mixture=atoms are together physically

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​Elements

• Atoms bond to form a molecule through a chemical reaction

​Elements Compounds Mixtures

The whole number, usually located in a corner is the atomic number. It represents the number of protons​

The other number, usually followed by several places beyond the decimal, is the atomic mass.​

Basic information from the periodic table:​

Elements- made up of only one type of atom

• Groups/families=up & down column; similar characteristics

• Period=left to right row

• Metal=left of the step; luster; malleable; ductile; conductors

• Nonmetal= right of the step; dull; brittle; nonconductor; usually gas

•  Metalloids= properties of metals & nonmetals along step

• Group 17= halogens

• Group 18= noble gases; inert (do not react)

• Group 1= alkali metals; most reactive

• Atoms bond to form a molecule  through a chemical reaction

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• Physical changes: Are changes to the appearance without changing a substance’s identity.

• Signs of a physical reaction: Dissolving, changing color with dyes, and breaking/ smashing.

• Chemical change: Observations that DO change the identity of the object making a NEW substance.

• Signs of chemical reaction: heat, light, gas, precipitate, color change, smell change

• Elements differ in the # of Protons

• The atomic # of an element is defined by the # of protons

• The # of electrons of each element determines the properties of that element (i.e. gas, liquid, solid, metal. nonmetal)

• Compounds involve two different elements bonded together (Ex: H2O & CO2)