Matter

• What is Chemistry? The study of matter and the changes it undergoes.
• What is the Scientific method? A way of approaching a problem in a logical fashion. The scientific method has three distinct steps.
• Hypothesis


  A tentative explanation for a set of observations.
• Law: Concise verbal or mathematical statement of a relationship between phenomena that is always the same under the same conditions.

  
  

  A law is an observation that applies to many things. (It is the way things are.) A law is not a rationalization explaining what is happening in a system. It is what is happening in a system.
• Theory: A unifying principle that explains a body of facts and/or laws that are based on them. A theory (model) is based on a series of hypotheses.
• What is Matter?

  Anything that occupies space and has mass.
• What is a substance? A forma of matter that has a definite (constant) composition and distinct properties.
• What is a mixture? A combination of 2 or more substances in which the substances retain their distinct identities. A mixture can be created or separated by PHYSICAL means.
• What are the types of mixtures? Homogeneous: The composition of the mixture is the same throughout.

  Heterogeneous: The composition is not uniform.
• What is an element? A substance that can not be separated into simpler substances by chemical means. The 114 Elements of the periodic table, meanwhile there are 119 in the updated one.
• What is a compound? A substance composed of atoms of two or more elements chemically united in fixed proportions.
• What are the 3 states of matter? 1. Solid

  2. Liquid

  3. Gas

  Matter can change states when temperature changes without changing its chemical composition.
• What are the physical properties of matter? Properties that can be measured and observed without changing the composition or identity of the substance.
• Examples of physical properties of matter: Melting point, boiling point, smell, opacity, viscosity, density, magnetic attraction.
• What are the chemical properties of matter? Any property of a substance that cannot be studied without converting the substance into some other substance.
• Examples of chemical properties of matter: Digestion, combustion, reactivity with water, PH, electromotive force.
• Categories of measurable properties: 1. Extensive properties

  2. Intensive properties.
• extensive properties: The measured value depends on the amount of matter being considered.
• Examples of extensive properties: 1. mass 2. enthalpy 3. entropy 4. length 5. volume
• Define intensive properties: The measured value does NOT depend on how much matter is being considered. (not additive)
• Examples of intensive properties

  1. Density

  2. Temperature
• Define SI Units: International System of Units - (from French: Systeme Internationale d'Unites)
• Define weight: The measure of gravitational force exerted on an object
• How to measure mass? kilogram (kg) is too big, the gram (g) is more convenient in chemistry.

  
  

  1 kg = 1000 g = 1 x 10³ g
• How to measure volume? For chemistry cubic meter (m³) is too large, so it is better to use cubic centimeter (cm³) or cubic decimeter (dm³)
• Equation to convert K to ºC: ºC = K - 273.15
• Equation to convert ºC to K: K= ºC + 273.15
• Equation to convert ºC to ºF: ºF = (1.8 x ºC) + 32
• Equation to convert ºF to ºC: ºC = (ºF - 32) / 1.8
• What is density? The mass of a substance divided by its volume
• What is scientific notation? Scientific notation helps us handle very large and very small numbers.

  N x 10^n, where N is a number between 1 - 10 and n is a positive or negative integer.
• Define Significant figures: all the digits that can be known precisely in a measurement, plus a last estimated digit
• Dimensional Analysis: A technique base on the relationship between different units that express the same physical quantity.
• Accuracy: How close a measurement is to the true value of the quantity that was measured.

  -> Highly accurate measurements are usually precise too.
• Precision: Refers to how closely tow or more measurements of the same quantity agree with one another