Midterm Exam Flashcards
Identify Matter vs. Non-matter?
- Matter: Anything that has mass and occupies space
- Non-matter: Anything that does not have mass and/or does not occupy space
- Example: Light, heat, air
What is Chemistry?
-The study of the composition of matter and the changes that matter undergoes
List the Steps of the Scientific Method
- Make observations
- Proposing 2 hypotheses (one is null)
- Experimentation
- Form a theory or Scientific Law
Identify the manipulated, responding, and control variables in an experiment
- The manipulated variable in an experiment is the independent variable because it is changed
- The responding variable is the dependent variable because it reacts depending on the independent variable
- The control variables in an experiment are the things that are kept constant during an experiment such as heat, an amount of something, etc.
Identify extensive and intensive properties
- Extensive: A property that depends on the amount of matter in a substance (mass, volume, height, length)
- Intensive: Do not depend on the amount of matter present (malleability, color, boiling point, melting point/freezing point, density)
Compare the properties of solids, liquids, and gases
- Solids: Definite shape, definite volume, particles packed tightly together, almost incompressible, expands when heated
- Liquids: No definite shape, particles flow freely, fixed volume, almost incompressible, expands when heated
- Gases: takes shape and volume of container, particles are spread out, easily compressible.
Define physical and chemical change
- Physical change: some properties of a material change, but the composition of the material does not change
- Chemical change: Any change that results in the formation of a new chemical substance
Provide examples of physical and chemical change
- Physical: Ice melting to become water, water freezing into ice
- Chemical: mixing sodium and chlorine to made sodium chloride/ salt (NaCl)
Explain why a physical change is reversible or irreversible
- Irreversible: cannot go back to normal (burned paper cannot be turned back into paper)
- Reversible: cannot go back to normal (ice can be turned back into water)
Explain how chemical reactions can be identified
- Production of Gas
- Production of precipitate
- Color change
- Transfer of Energy
Identify the reactants and products of a chemical change
- Reactant: a substance present at the start of the reaction
- Product: A substance produced in the reaction
Define the law of conservation of mass
-Law of conservation of mass: In any physical change or chemical reaction, mass is conserved
Explain how the law of conservation of mass applies to both physical and chemical changes
- Physical change: The product before and after the change will weigh the same (has the same mass).
- Chemical change: In a chemical reaction, the mass of the products is always equal to the mass of the reactants.
Determine the atomic number and mass of an electron
- Compares the relative masses of all elements to carbon-12. #= weighted average of all isotopes of an element. (It’s units are called atomic mass units)
- Atomic #= number of protons
Calculate atomic mass of an element from the mass and percent of each isotope
-Atomic mass (isotope’s mass x % natural abundance)
Explain how electrons move from one energy level to another
- For electrons to move from a lower energy level to a higher energy level, they absorb energy while emitting light
- For electrons to move from a higher energy level to a lower energy level, they release energy while emitting light
Rutherford’s Atomic model vs. Bohr Model
- RAM: Only explained a few simple properties of the atom
- RAM: Could not explain the chemical properties of an element
- RAM: Could not explain why elements heated to higher temps give off colored light
- BM: Showed how energy of an atom changes when absorbing or emitting light
- BM: An electron is only found in specific circular motions, or orbits, around the nucleus
- BM: Explains that when an atom emits light it is moving from one energy level to another
- BM: Each orbit has a different energy level and fixed energy
- Both have something to do with energy
Bohr Model vs. Quantum Mechanical Model
- BM: Only explained the energy in simple atoms like hydrogen
- QMM: Mathematical equation to describe the behavior of an electron in a hydrogen atom
- QMM: Does not specify the exact path of an electron around the nucleus
- QMM: Orbitals use probability to predict a region of space where an electron is found at any given time
- BM: 2D, QMM: 3D
How to write an electron configureation
- Ways to show
- Aufbau diagram
- Standard Electron Configuration
- Orbital filling diagram
- Electrons occupy the lower energy levels first (Aufbau principle)
- To be in the same orbital, electrons must have opposite spin (Pauli exclusion principle)
- Ever orbital subshell gets 1 electron before receiving another and have parallel spin ( Hund’s rule)
Explain why elements and compounds release different colored light
- The orbitals contain different energy levels when they are transferred
- Red= lowest
- Purple= highest
Who created the periodic table?
- Mendeleev
- Based on increasing atomic mass
Identify a substance as a metal, metalloid, or nonmetal
- Metal: shiny, malleable, good conductor of electricity, ductile, mostly solid at room temp
- Non-Metal: dull, brittle, poor conductor
- Metalloid: depending on conditions can act like metal or nonmetal, poor conductor
