Questions and Answers
What is the atomic number of an atom that has 6 protons, 6 neutrons, and 6 electrons?
6
What refers to atoms with the same atomic number, but different atomic masses?
Isotopes
Fluorine's atomic number is 9 and its atomic mass is 19. How many neutrons does fluorine have?
10
An uncharged atom of boron has an atomic number of 5 and an atomic mass of 11. How many protons does boron have?
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Which type of bond is joining the two hydrogen atoms?
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What refers to two or more atoms held together by covalent bonds?
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This atom can form up to how many single covalent bond(s)?
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What type of bond joins these two oxygen atoms?
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Atoms with the same number of protons but with different electrical charges are called?
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In salt, what is the nature of the bond between sodium and chlorine?
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An ionic bond involves?
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The brackets are indicating what type of bond?
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What name is given to the bond between water molecules?
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Water readily sticks to many other substances, a property called?
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Water striders can skip across the surface of ponds due to water's?
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Which best describes how charges are distributed on a water molecule?
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Relative to other substances, why does water tend to resist changes in temperature?
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Water is sometimes called the 'universal solvent.' Is that accurate?
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In a neutral solution, the concentration of what is equal to the concentration of hydroxide ions?
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Study Notes
Atomic Structure and Isotopes
- Atomic number of an atom is determined by the number of protons, e.g., an atom with 6 protons has an atomic number of 6.
- Isotopes are variants of an element that have the same number of protons but differ in atomic mass due to varying numbers of neutrons.
Neutrons and Atomic Mass
- Fluorine, with an atomic number of 9 and atomic mass of 19, has 10 neutrons (atomic mass = protons + neutrons, 19 - 9 = 10).
- Boron has an atomic number of 5, indicating it has 5 protons.
Chemical Bonds
- Covalent bonds occur when two atoms share electron pairs, e.g., the bond between two hydrogen atoms.
- Molecules are formed when two or more atoms are held together by covalent bonds.
- An atom typically can form up to 4 single covalent bonds due to 4 electrons in its outer shell.
- Double covalent bonds involve the sharing of two pairs of electrons, as seen with oxygen atoms.
Ions and Ionic Bonds
- Atoms that have identical numbers of protons but different electrical charges become ions.
- Ionic bonds form through the attraction between positively and negatively charged ions, exemplified by sodium chloride (salt).
Hydrogen Bonds and Molecular Interactions
- Hydrogen bonds occur when a hydrogen atom with a net positive charge is attracted to a negatively charged atom, such as oxygen.
- Water molecules are interconnected by hydrogen bonds, which exhibit properties of cohesion (molecules sticking together) and adhesion (sticking to other substances).
Water's Unique Properties
- Water demonstrates strong cohesion, enabling certain insects, like water striders, to skim the surface due to high surface tension.
- Water maintains a relatively stable temperature due to its high cohesion; temperature changes induce energy used to adjust hydrogen bonds, not just kinetic motion.
- Often referred to as the "universal solvent," water dissolves most substances, although it does not dissolve hydrophobic materials like oils.
Ion Concentration in Solutions
- In neutral solutions, the concentrations of hydrogen ions (H⁺) and hydroxide ions (OH⁻) are equal, maintaining a balance essential for various biological and chemical processes.
Studying That Suits You
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Description
Test your knowledge of atomic structure and isotopes with these flashcards from Biology Chapter 2. Each card provides a key concept related to atomic numbers and their significance in understanding elements. Perfect for quick review and memorization before exams.
