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Questions and Answers
How many significant figures are in the number 0.02050?
How many significant figures are in the number 0.02050?
The atomic number of an element represents the sum of protons and neutrons in an atom's nucleus.
The atomic number of an element represents the sum of protons and neutrons in an atom's nucleus.
False
What is the primary difference between isotopes of the same element?
What is the primary difference between isotopes of the same element?
They have different numbers of neutrons
In alpha decay, a nucleus emits an ______ containing 2 protons and 2 neutrons.
In alpha decay, a nucleus emits an ______ containing 2 protons and 2 neutrons.
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Which of the following is NOT true about core electrons?
Which of the following is NOT true about core electrons?
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Trailing zeros in a whole number are always significant.
Trailing zeros in a whole number are always significant.
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What is nuclear fission?
What is nuclear fission?
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Match the following terms with their definitions:
Match the following terms with their definitions:
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What type of ion is formed when an atom loses electrons?
What type of ion is formed when an atom loses electrons?
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A physical change results in the formation of a new substance.
A physical change results in the formation of a new substance.
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What is the name given to ions that are made up of more than one atom?
What is the name given to ions that are made up of more than one atom?
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In the electron configuration of Carbon, 1s² 2s² 2p², the number of electrons in the 2p orbital is ______
In the electron configuration of Carbon, 1s² 2s² 2p², the number of electrons in the 2p orbital is ______
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Match the following elements with their respective ionic charges:
Match the following elements with their respective ionic charges:
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Which of the following is an example of a chemical change?
Which of the following is an example of a chemical change?
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Transition metals can only have one charge or oxidation state.
Transition metals can only have one charge or oxidation state.
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The rule that dictates that the total positive charge in an ionic compound must equal the total negative charge is the Rule of ______
The rule that dictates that the total positive charge in an ionic compound must equal the total negative charge is the Rule of ______
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Write the formula for the ionic compound formed when Magnesium (Mg) reacts with Chlorine (Cl).
Write the formula for the ionic compound formed when Magnesium (Mg) reacts with Chlorine (Cl).
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What is the correct formula for the ionic compound formed between Sodium (Na+) and Oxygen (O2-)?
What is the correct formula for the ionic compound formed between Sodium (Na+) and Oxygen (O2-)?
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Study Notes
Significant Figures (Sig Figs)
- Significant figures (sig figs) represent digits in a measurement that provide meaningful information on its precision.
- Non-zero digits are always significant.
- Zeros between non-zero digits are significant.
- Leading zeros are not significant.
- Trailing zeros in a decimal number are significant.
- Trailing zeros in a whole number (without a decimal) are not significant.
- Understanding significant figures is important to correctly round results in calculations.
Atomic Number and Atomic Mass
- Atomic Number (Z): The number of protons in an atom, defining the element.
- Example: Oxygen (atomic number 8) has 8 protons.
- Atomic Mass (A): The sum of protons and neutrons in an atom's nucleus (atomic weight).
- Example: Carbon (atomic mass ~12 amu) has 6 protons and 6 neutrons.
Isotopes and Radioactive Decay
- Isotopes: Different versions of the same element with varying neutron counts, changing atomic mass.
- Example: Carbon-12 (6 protons, 6 neutrons) and Carbon-14 (6 protons, 8 neutrons).
- Stable Isotopes: Do not change over time. Example: Carbon-12.
- Radioactive Isotopes: Decay over time, emitting radiation. Example: Carbon-14 decaying into Nitrogen-14.
Nuclear Reactions
- Nuclear reaction: A change in the atom's nucleus (not electrons), involving protons and neutrons.
- Alpha Decay: Nucleus emits an alpha particle (2 protons + 2 neutrons).
- Example: Uranium-238 → Thorium-234 + α particle.
- Beta Decay: A neutron transforms into a proton, releasing a beta particle (electron).
- Nuclear Fission: Splitting a heavy atom, releasing energy.
- Example: Uranium-235 fission.
Valence and Core Electrons
- Valence Electrons: Electrons in the outermost shell, dictating bonding behavior.
- Example: Oxygen (O) has 6 valence electrons.
- Core Electrons: Inner shell electrons not involved in bonding.
- Example: Oxygen has 2 core electrons in its first shell.
Ions and How They Form
- Ions: Charged atoms formed by gaining or losing electrons.
- Cations: Positive ions formed by losing electrons.
- Example: Sodium (Na) losing 1 electron to become Na⁺.
- Anions: Negative ions formed by gaining electrons.
- Example: Chlorine (Cl) gaining 1 electron to become Cl⁻.
Ionic Compounds
- Ionic compounds: Formed when metals transfer electrons to nonmetals, creating oppositely charged ions that attract.
- Example: Sodium (Na) to Chlorine (Cl) forming NaCl (table salt).
Writing Formulas for Ionic Compounds
- Balancing charges: Determine ion charges and balance positive and negative charges.
- Example 1: Mg²⁺ and Cl⁻ form MgCl₂
- Example 2: Na⁺ and O²⁻ form Na₂O
Polyatomic Ions
- Polyatomic ions: Ions with more than one atom, acting as a single unit with a charge.
- Example: ammonium (NH₄⁺), sulfate (SO₄²⁻), nitrate (NO₃⁻)
- Use parentheses for multiple instances: Ca(SO₄)₂
Transition Metals
- Transition metals: Groups 3-12, exhibiting multiple charges (oxidation states).
- Specify charge using Roman numerals:
- Example: Copper(I) chloride (CuCl), Copper(II) chloride (CuCl₂).
Physical vs. Chemical Changes
- Physical Change: Changes state or appearance, but substance remains the same.
- Examples: Ice melting, paper tearing.
- Chemical Change: Forms new substances.
- Examples: Burning wood, iron rusting.
Electron Configurations
- Electron configuration: Shows arrangement of electrons in atomic orbitals.
- Aufbau Principle: Fill lowest energy levels first.
- Pauli Exclusion Principle: Each orbital holds a maximum of 2 electrons.
- Hund's Rule: Fill each orbital individually before pairing electrons.
- Example: Carbon (C) electron configuration: 1s² 2s² 2p²
Binary Ionic Compounds
- Binary ionic compounds: Formed from 2 different elements (metal and nonmetal).
- Example 1: Mg²⁺ and Cl⁻ form MgCl₂
- Example 2: Na⁺ and S²⁻ form Na₂S
Rule of Zero Change
- Rule of Zero Change: Total positive charge from cations must equal total negative charge from anions for a neutral compound.
- Example: Mg²⁺ + 2Cl⁻ = MgCl₂ (zero charge).
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Description
This quiz covers essential concepts in chemistry including significant figures, atomic numbers, atomic mass, and isotopes. Understanding these principles is crucial for accurately interpreting measurement precision and elemental characteristics. Test your knowledge and solidify your grasp of foundational chemistry topics.
