Name: _______________________________________________ Date: _____________ Period: ______ NOTES

Chemistry Notes: Chemical Reactions

What are Physical Properties?

  • Physical properties can be ___________________ and measured without changing the _______________ of the substance.
  • _______________ Changes:
  • _________________ Point: the temperature at which a substance ________ (or ___________…they’re just the reverse of each other, and it happens at the same temperature!). The freezing/melting point of water is _____ degrees C.
  • __________ Point: the temperature at which a liquid boils (substances changes from a liquid to a ______). The boiling point of water is _____ degrees C.
  • Different _________________ melt and boil at different ___________________, so we can use this to identify an unknown substance.
  • Density: _________________________; how much mass is in a given amount of ____________ (volume). Every substance has a _____________ density that stays the same no matter how __________________________ the sample is, so we can use this to identify an unknown substance.
  • Other physical properties: ____________, __________, color, smell, etc.

Phases of matter: Solids

  • Solids: atoms are packed ______________ together in a rigid _______________. They still have some ___________, so they ______________ in place

Phases of matter: Liquids

  • Liquid: at the ______________ point, atoms acquire enough energy to _____________ _____________; the pattern loosens up, and the substance can _____________

Phases of matter: Gases

  • Gas: at the _____________ point, atoms have enough energy to change to a ________. In a gas the atoms or molecules move about _______________ and ________________ randomly with the walls of a container and with __________________________. The distance between molecules in a gas is much ______________ than that in a solid or a _________. (In a gas, the particles have LOTS of __________ and bounce off the walls!)

Phases of matter at the atomic level: Density

  • As a substance goes from a ___________ to a liquid to a _________, the _____________ of the substance __________________. This is because as the pattern gets ___________, the atoms/molecules get ______________ apart.
  • The exception is ___________: ice ____________ on liquid water, meaning ice (a solid) is __________ dense than water (a liquid)

Draw the Phases of Matter

What are Chemical Properties?

  • Chemical properties can be observed only when substances ___________ or do not react _________________ with one another, that is, when they undergo a ______________ in composition.  A ________________ property of one substance usually involves its ability to react or not react with another specific ___________________.
  • Examples:
  • Reacting with _______________: The ability of a substance to ____________ is a chemical property that involves a substance reacting _____________ with oxygen to produce light and heat (_________). Reacting with oxygen __________ occurs when iron _________.
  • Reacting with an _________: some metals react with acids to form ____________, while ______________ solutions (we’ll talk about later) react with acids to form ________________ solutions.

Chemical Properties: Acids, Bases, and Neutral solutions

  • Does it _______________ in water?
  • Water is often called the “_____________________________________” because so many substances _______________________________ in it.
  • Solutions can be ________________, basic, or _________________.
  • Substances that form ____________ and _____________ must be dissolved in _____________ before you can tell if they’re acids or bases. Once dissolved in water, the substances release ___________.
  • pH: a measure of how ____________ or basic a solution is.
  • The pH scale goes from 1 to _______. A pH of _____ is a ______________ solution (neither an acid nor a base), a pH __________ than 7 is an _________, and a pH greater than _______ is a _____________.

Substances can Change

  • Substances change in _____ ways:
  • __________________ Change: a change that occurs that does not change the _________________ of the substance (it’s still the same “stuff”)
  • ______________ change, ______________ change, change in size or shape, change in physical properties
  • __________________ Change: a change that occurs that changes the ________________ of the substance (turns it into something else). Results in the formation of a _______________________________________.
  • ______________ paper, digesting food, change in chemical properties
  • When a chemical change occurs, it is called a chemical ____________

What is a Chemical Reaction?

  • Chemical Reaction: when 2 or more substances _____________ (interact) to form a ___________ substance.
  • Happens when substances (compounds or elements) ________________ (hit each other) and interact.
  • In a chemical reaction, a ________________ change takes place (the substances you _______________ with become _________ substances).
  • ________________ react to form _________________.
  • Reactants: the substances you _____________ with
  • Products: the substances you ___________ with
  • Abbreviation for reaction: ___________

How do I know if a Chemical Change or Reaction has occurred?

  • __________________ of a chemical reaction:
  1. ______________ Change
  • Iron turns red-brown when it reacts with _________________ (rust)
  • exceptions: food coloring or ________________ something
  1. ________________________ Change
  • Wood __________________—increased temperature
  • Exceptions: ______________ water, sunshine heating water in a lake
  1. Formation of a ______________
  • ________________ form
  • Exception: ________________ liquid
  1. Formation of a ________________________
  • Precipitate: a _____________ that forms from combining 2 _________

What is a Reaction Rate?

  • Reaction ___________: how _____________ it takes for the reaction to occur.
  • Reactions occur at _________________ rates, from very __________ to very _____
  • The reaction rate can be _________________ by:
  • Changing the __________________________ of the reactants
  • As concentration increases, reaction rate ___________________ (speeds up)
  • Increase in concentration means more ________________ present that can react, leading to a ______________ and/or ______________ reaction.
  • Changing the __________________ of the reaction mixture
  • As temperature increases, reaction rate _________________
  • Increased temperature makes the particles of a substance _______________  This increase in motion allows reactants to _____________ and interact more frequently (_________________ reaction rate).  
  • ___________________________ of the reactants
  • Increased surface area=___________________ reaction rate
  • If there’s more surface area, there’s more particles that can ______________ and interact
  • Presence of a _________________
  • Catalyst: something that _______________ a reaction, but is not ________________ in the reaction.