Multiple Choice
How many protons and electrons are present in a neutral atom of strontium (Sr)?
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Table of contents
- 1. Intro to General Chemistry3h 48m
- Classification of Matter18m
- Physical & Chemical Changes19m
- Chemical Properties7m
- Physical Properties5m
- Intensive vs. Extensive Properties13m
- Temperature12m
- Scientific Notation13m
- SI Units7m
- Metric Prefixes24m
- Significant Figures9m
- Significant Figures: Precision in Measurements8m
- Significant Figures: In Calculations14m
- Conversion Factors16m
- Dimensional Analysis17m
- Density12m
- Density of Geometric Objects19m
- Density of Non-Geometric Objects7m
- 2. Atoms & Elements4h 16m
- The Atom9m
- Subatomic Particles15m
- Isotopes17m
- Ions27m
- Atomic Mass28m
- Periodic Table: Classifications11m
- Periodic Table: Group Names8m
- Periodic Table: Representative Elements & Transition Metals7m
- Periodic Table: Element Symbols6m
- Periodic Table: Elemental Forms6m
- Periodic Table: Phases8m
- Periodic Table: Charges20m
- Calculating Molar Mass10m
- Mole Concept30m
- Law of Conservation of Mass5m
- Law of Definite Proportions10m
- Atomic Theory9m
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- Millikan Oil Drop Experiment7m
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- 3. Chemical Reactions4h 10m
- Empirical Formula18m
- Molecular Formula20m
- Combustion Analysis38m
- Combustion Apparatus15m
- Polyatomic Ions24m
- Naming Ionic Compounds11m
- Writing Ionic Compounds7m
- Naming Ionic Hydrates6m
- Naming Acids18m
- Naming Molecular Compounds6m
- Balancing Chemical Equations13m
- Stoichiometry16m
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- Percent Yield19m
- Mass Percent4m
- Functional Groups in Chemistry11m
- 4. BONUS: Lab Techniques and Procedures1h 36m
- 5. BONUS: Mathematical Operations and Functions48m
- 6. Chemical Quantities & Aqueous Reactions3h 53m
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- Molarity18m
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- Root Mean Square Speed9m
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- 8. Thermochemistry2h 37m
- Nature of Energy6m
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- Internal Energy8m
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- Constant-Pressure Calorimetry24m
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- Thermal Equilibrium8m
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- Hess's Law23m
- 9. Quantum Mechanics2h 58m
- Wavelength and Frequency6m
- Speed of Light8m
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- Bohr Model14m
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- Introduction to Quantum Mechanics5m
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- Quantum Numbers: Nodes6m
- 10. Periodic Properties of the Elements3h 9m
- The Electron Configuration22m
- The Electron Configuration: Condensed4m
- The Electron Configurations: Exceptions13m
- The Electron Configuration: Ions12m
- Paramagnetism and Diamagnetism8m
- The Electron Configuration: Quantum Numbers16m
- Valence Electrons of Elements12m
- Periodic Trend: Metallic Character3m
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- 11. Bonding & Molecular Structure3h 29m
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- 12. Molecular Shapes & Valence Bond Theory1h 58m
- 13. Liquids, Solids & Intermolecular Forces2h 23m
- Molecular Polarity10m
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- Intro to Henry's Law4m
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- The Colligative Properties14m
- Boiling Point Elevation16m
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- Osmosis19m
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- 15. Chemical Kinetics2h 53m
- 16. Chemical Equilibrium2h 29m
- 17. Acid and Base Equilibrium5h 2m
- Acids Introduction9m
- Bases Introduction7m
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- Oxyacids10m
- Bases14m
- Amphoteric Species5m
- Arrhenius Acids and Bases5m
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- Diprotic Acids and Bases8m
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- 18. Aqueous Equilibrium4h 47m
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- Titrations: Diprotic & Polyprotic Buffers32m
- Solubility Product Constant: Ksp17m
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- Selective Precipitation9m
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- 19. Chemical Thermodynamics1h 50m
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- 21. Nuclear Chemistry2h 37m
- Intro to Radioactivity10m
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- Band of Stability: Alpha Decay & Nuclear Fission10m
- Band of Stability: Beta Decay3m
- Band of Stability: Electron Capture & Positron Emission4m
- Band of Stability: Overview14m
- Measuring Radioactivity7m
- Rate of Radioactive Decay12m
- Radioactive Half-Life16m
- Mass Defect19m
- Nuclear Binding Energy14m
- 22. Organic Chemistry5h 7m
- Introduction to Organic Chemistry8m
- Structural Formula8m
- Condensed Formula10m
- Skeletal Formula6m
- Spatial Orientation of Bonds3m
- Intro to Hydrocarbons16m
- Isomers11m
- Chirality15m
- Functional Groups in Chemistry11m
- Naming Alkanes4m
- The Alkyl Groups9m
- Naming Alkanes with Substituents13m
- Naming Cyclic Alkanes6m
- Naming Other Substituents8m
- Naming Alcohols11m
- Naming Alkenes11m
- Naming Alkynes9m
- Naming Ketones5m
- Naming Aldehydes5m
- Naming Carboxylic Acids4m
- Naming Esters8m
- Naming Ethers5m
- Naming Amines5m
- Naming Benzene7m
- Alkane Reactions7m
- Intro to Addition Reactions4m
- Halogenation Reactions4m
- Hydrogenation Reactions3m
- Hydrohalogenation Reactions7m
- Alcohol Reactions: Substitution Reactions4m
- Alcohol Reactions: Dehydration Reactions9m
- Intro to Redox Reactions8m
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- Aldehydes and Ketones Reactions6m
- Ester Reactions: Esterification4m
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- Carboxylic Acid Reactions4m
- Amine Reactions3m
- Amide Formation4m
- Benzene Reactions10m
- 23. Chemistry of the Nonmetals2h 39m
- Main Group Elements: Bonding Types4m
- Main Group Elements: Boiling & Melting Points7m
- Main Group Elements: Density11m
- Main Group Elements: Periodic Trends7m
- The Electron Configuration Review16m
- Periodic Table Charges Review20m
- Hydrogen Isotopes4m
- Hydrogen Compounds11m
- Production of Hydrogen8m
- Group 1A and 2A Reactions7m
- Boron Family Reactions7m
- Boron Family: Borane7m
- Borane Reactions7m
- Nitrogen Family Reactions12m
- Oxides, Peroxides, and Superoxides12m
- Oxide Reactions4m
- Peroxide and Superoxide Reactions6m
- Noble Gas Compounds3m
- 24. Transition Metals and Coordination Compounds3h 16m
- Atomic Radius & Density of Transition Metals11m
- Electron Configurations of Transition Metals7m
- Electron Configurations of Transition Metals: Exceptions11m
- Paramagnetism and Diamagnetism10m
- Ligands10m
- Complex Ions5m
- Coordination Complexes7m
- Classification of Ligands11m
- Coordination Numbers & Geometry9m
- Naming Coordination Compounds22m
- Writing Formulas of Coordination Compounds8m
- Isomerism in Coordination Complexes15m
- Orientations of D Orbitals4m
- Intro to Crystal Field Theory10m
- Crystal Field Theory: Octahedral Complexes5m
- Crystal Field Theory: Tetrahedral Complexes4m
- Crystal Field Theory: Square Planar Complexes4m
- Crystal Field Theory Summary8m
- Magnetic Properties of Complex Ions9m
- Strong-Field vs Weak-Field Ligands6m
- Magnetic Properties of Complex Ions: Octahedral Complexes11m
2. Atoms & Elements
The Atom
Struggling with General Chemistry?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
An atom has an atomic number of 15 and a mass number of 31. How many protons are present in this atom?
A
16
B
46
C
15
D
31
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Verified step by step guidance1
Recall that the atomic number of an atom represents the number of protons in its nucleus.
Identify the atomic number given in the problem, which is 15.
Understand that the mass number is the sum of protons and neutrons, but it does not affect the number of protons directly.
Since the atomic number is 15, the atom has 15 protons.
Therefore, the number of protons in the atom is equal to the atomic number, which is 15.
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