What is Chemistry/Matter?

• What is Chemistry?

  • Chemistry is the study of composition, structure, and properties of matter, the processes that matter undergoes, and the energy changes that accompany these changes.

• What is Matter?

  • Matter has mass and takes up space

  • Everything around you is composed of matter

    • What is not matter: (energy, light, heat, sound, etc.)

  • There are 3 states of matter we focus on in this class

    • Gas

    • Liquid

    • Solid

States of Matter

• Each addition of energy creates a change in the state of matter

• More energy = more movement = change in state of matter

States of Matter from least to most energy

1. Bose-Einstein Condensate

   • Occurs when objects reach absolute zero temperature

   • Atoms become waves, then become one whole entity

2. Solid

3. Liquid

4. Gas

5. Plasma

   • Lightning, Aurora, Gas in neon signs

Basics of Matter & Vocabulary

• Volume: Amount of 3D space an object occupies

• Mass: Measures the amount of matter

• Matter: Has mass and takes up space

• Weight: Pull of gravity on matter

• Atom: Smallest unit of an element

• Element: Pure substance made of one type of atom

• Compound: Pure substance made of 2 or more elements that are chemically bonded

  • Example: NaCI, H₂O, CaCO₃

• Molecule: Pure substance made of 1 element, chemically bonded

  • Example: H₂, O₂, S₈

• Pure Substance: Consists of 1 type of matter

  • Element, Compound, Molecules

• Mixture: 2 or more types of matter

  • Can be a homogeneous or heterogeneous mixture

• Homogeneous Mixture:

  • Same Throughout

  • Looks like one mixture

  • Uniform with no visual difference throughout

  • Examples: Vodka, Steel, Air, Rain

• Heterogeneous Mixture:

  • Different appearance throughout

  • Can see different parts of mixture

  • Examples: Cereal in milk, ice in soda, soil, sand

Mixtures

Methods to separate mixtures:

1. Filtration

   • Separates heterogeneous

   • Examples:

     • Sand in water

     • Any insoluble solid in water

2. Distillation

   • Can separate homogeneous

     • Also separates oil and water

   • Heats up the mixture

   • Liquid becomes gas

   • Gas travels through tube into container

   • Gas condenses into water in separate container

   • Evaporation can be done instead but doesn’t preserve the water

3. Evaporation

• Separates Homogeneous

• Same as distillation but doesn’t save the liquid

• Only solid remains

Practice:

How to identify matter:

Physical & Chemical Properties of Matter

• Physical Changes: Matter does not change

  • May look different

  • Same matter

  • Salt in water, still salt

  • Coloring on paper, still paper

• Chemical Changes: Changes 1 substance into something else

  • Couldn’t change substances that have undergone a chemical change back to their original form through distillation or filtering

  • Different substance is formed

How to identify the type of change:

• Signs of a chemical change

  • Evolution of bubbles

  • Precipitate formed - insoluble solid in water

  • Heat or light released

  • Color change

• Usually use more than 1 sign to identify if a change occurred

• Examples of chemical properties of matter (Extensive Properties)

  • Ability to react with oxygen

  • Ability to react with acids

  • Reacts with water

  • Does not react with oxygen

  • Does not react with acids

  • Does not react with water

• Examples of physical properties of matter (Intensive Properties)

  • Boiling point

  • Melting point

  • Description

    • Color

    • Hardness

    • Malleability - ability to form into sheets

    • Ductility - Ability to form into wires

  • Density

Intensive vs Extensive Properties

• Intensive Property:

  • Does not depend on the amount of substance present.

  • Examples: Density, boiling point, color, temperature.

  • Determination: Measure the property in a sample; if it remains constant regardless of sample size, it is intensive.

• Extensive Property:

  • Depends on the amount of substance present.

  • Examples: Mass, volume, total energy, length, shape

  • Determination: Measure the property in a sample; if it changes with the size of the sample, it is extensive.

Sig Figs Notes

Importance of Measurement Accuracy

Example:

Significant Figures Rules

• All non-zero numbers significant

• ZERO’S

  • Leading: never count (ie. 0.0000003 = 1 sig fig)

  • Captive: always count (ie. 1.0000045 = 8 sig fig)

  • Trailing: only count if number has a decimal point

    • 100 = 1 sig fig

    • 100. = 3 sig fig

    • 150.0 = 4 sig fig

• Exact numbers – unlimited significant figures

  • Examples 1 atm = 14.7 psi

Simpler Rules

• If the number is has a decimal point the arrow points to the right and crosses all zeros until it hits a non-zero number.

• If the number has no decimal point the arrow points to the left and crosses all zeros until it hits a non-zero number.

Example:

Rounding, Addition, Subtraction, Multiplication and Division Rules

Scientific Notation:

• Used to write very small or very large numbers

• Writes numbers as a decimal multiplied by 10 to the power of something

• Examples

  • 253,000,000 = 2.53×10^8

  • 0.000047 = 4.7×10^-5

Density

• Amount of mass an object takes up in a

  specific amount of volume

• Formula: Density = Mass/Volume (D=M/V)

• Which is denser: cork or tin?

Factor Label Notes

Qualitative Data: Interpretation based, descriptive, or relating to language

Quantitative Data: Numbers based, countable, or measurable

Quantities vs. Units

SI System

• SI system created to have a standard set of units used for measurements

• Mass = kg

• Length = m

• Time = s

• Temperature = K

Metric System Prefixes