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Chemistry Sci Quiz
| Question | Answer |
|---|---|
| Dalton's Theory | Atoms of the same element are identical (same mass and properties). |
| Thomson's Discovery | Discovered electrons (negative charges). Since atoms are neutral, he concluded they must also have positive charges. |
| Rutherford's Gold Foil Experiment | Shot positive particles at gold foil. Most passed through, implying atoms are mostly empty space with a small, dense, positive nucleus. |
| Bohr's "Planetary" Model | Electrons orbit the nucleus in specific, fixed paths (energy levels), like planets around the sun. This improved upon Rutherford's model by explaining why electrons don't crash into the nucleus. |
| Schrödinger's Model (Quantum Mechanical): | The most accurate model. It describes electrons as clouds of probability (orbitals) rather than fixed paths. |
| Atomic Number: | The number of protons in an atom's nucleus. |
| Mass Number | The sum of protons and neutrons in the nucleus. |
| Neutral Atoms | The number of electrons equals the number of protons because opposite charges cancel out to create a neutral charge. |
| Calculating Neutrons | Mass Number - Atomic Number = Number of Neutrons. |
| APEMAN: A mnemonic to help remember: | Atomic number = Protons = Electrons (in a neutral atom) Mass number + Atomic number = Neutrons |
| Organization | Elements are arranged by increasing atomic number. Mendeleev's original table was organized by atomic mass and left gaps for undiscovered elements. |
| Metalloids: | Elements along the "stair-step" line that have properties of both metals and nonmetals. |
| Groups (Columns): | Elements in the same group have the same number of valence electrons and similar chemical properties. |
| Periods (Rows): | Elements in the same period have the same number of electron shells. |
| Alkali Metals (Group 1) | Very reactive, never found as free elements in nature because they readily form compounds. |
| Transition Metals: | Harder, denser, and have higher melting points than alkali metals. |
| Noble Gases (Group 18) | Unique because they have a full outer shell, making them unreactive (inert). |
| Lanthanides & Actinides | Placed below the main table to keep it compact. |
| Why Atoms Bond: | To become more stable by achieving a full outer electron shell (following the Octet Rule). |
| Valence Electrons: | The electrons in the outermost shell of an atom. They determine how an atom will bond. |
| Compounds | Substances formed when two or more different elements chemically combine. |
| Octet Rule | Atoms tend to form bonds to get 8 valence electrons (except hydrogen and helium, which need 2). |
| Predicting Valence Electrons: | For main group elements, the group number often tells you the number of valence electrons (e.g., Group 1 has 1, Group 2 has 2, Group 13 has 3, etc.). |
| Metals | Conduct electricity and heat well; nonmetals are poor conductors (insulators). |
| Who proposed that electrons move in fixed, specific orbits? | Answer: Bohr |
| What does the M in APEMAN stand for? | Answer: Mass |
| Which group is known for being unreactive? | Noble Gases / Group 18 |
| How many valence electrons does Nitrogen (Group 15) have? | Answer: 5 |
| If an atom has an atomic number of 8 and a mass number of 17, how many neutrons does it have? | Answer: 17 - 8 = 9 |
| Mixtures | two or more substances together that are not chemically combined *The substances can be separated by physical means* |
| A pure substance is | made up of only one type of matter cannot be separated easily Examples: Carbon dioxide, gold, pure water, salt |
| Heterogeneous Mixture | You CAN see the different compounds Examples: Oil and water Sand and water Chocolate chip cookies |
| Homogeneous Mixture | You CANNOT see the different compounds (but they can still be separated) Examples: Salt water Iced Tea Mix and water Milk |
| Solutions | a homogeneous mixture of a solvent and one or more solutes |
| Solute | dissolves into the solvent (what is being dissolved) |
| Solvent | dissolves the solute (what is doing the dissolving) |
| Concentration | how much solute is present in a ratio to your solvent |
| Surface Area | more exposed, solubility increases (break up a tablet into pieces) |
| Pressure | the solubility of a gaseous solute increases as pressure on the solute increases |
Created by:
30patels