Questions and Answers
In a polar covalent bond, atoms share electrons unequally.
True
Buffers compensate for pH changes by releasing or absorbing H+ ions.
True
The exclusion of polar substances from the interior of a lipid bilayer is essential for cells to survive.
True
Water has a very large specific heat, which helps prevent temperature changes in large bodies of water, such as Lake Michigan or any ocean.
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A covalent bond is formed when atoms gain or lose electrons.
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An atom that has its outer energy level completely filled with electrons is highly reactive.
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Molecular geometries dictate the function of a molecule.
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Nitrogen is one of the four elements that make up 96% of the weight of living organisms.
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An atom is the smallest unit that retains the chemical and physical properties of an element.
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The formation of an extensive network of van der Waals forces between water molecules is the reason that the solid form of water floats, unlike most substances that transition from a liquid to a solid state.
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The tendency of water molecules to stick to the walls of root tubes, known as _____, aids in moving water from roots up to the tops of plants.
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Which property of water allows humans to cool off by sweating?
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A substance that cannot be broken down by ordinary chemical or physical means is a(n) ____.
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The region of space where an electron 'lives' most of the time is called a(n) ____.
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A solution with a pH of 10 is ____.
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Which element is a trace element?
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When an ionic compound such as table salt (NaCl) is dissolved in water, ____.
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The bonds in iodine gas (I2) are _____ bonds, while the bonds in SH2 are _____.
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In an acidic solution, ____.
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Bonds that are the result of electrical attractions between atoms that gain or lose valence electrons are called ____ bonds.
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How many key elements are living things composed of?
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An ______ is the simplest substance.
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___________ make up 96% of the weight of living organisms.
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The other 4 elements are Ca, P, K, Na, Cl, Mg, S which make up ____.
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Trace elements are essential for various biochemical reactions.
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Study Notes
Fundamental Concepts of Chemical Bonds and Properties of Water
- Polar Covalent Bonds: Electrons are shared unequally between atoms, leading to partial charges.
- Buffers: Compensate for pH changes by releasing or absorbing hydrogen ions (H+).
- Lipid Bilayers: The exclusion of polar substances is crucial for cell survival, maintaining a hydrophobic environment.
- Water's Specific Heat: High specific heat capacity stabilizes temperatures in large water bodies, important for climate regulation.
Misconceptions About Chemical Properties
- Covalent Bonds: Formed by the sharing of electrons, not gaining or losing them.
- Reactivity of Atoms: Atoms with full outer energy levels are typically not reactive (noble gases).
Molecular and Atomic Characteristics
- Molecular Geometries: Shape of a molecule is critical as it influences biological functions and interactions.
- Key Elements in Organisms: Nitrogen is one of the four elements (CHON) that constitute 96% of living organism’s mass.
- Atoms: Defined as the smallest unit retaining an element's chemical and physical properties.
Properties of Water
- Adhesion: Water molecules sticking to the walls of root tubes assists in water transport within plants.
- Heat of Vaporization: This property allows for effective cooling through sweating in humans.
- Solid Water: Ice floats due to lower density resulting from hydrogen bonding, not van der Waals forces.
Solutions and pH
- Basic Solutions: Solutions with a pH above 7, such as pH 10, are considered basic.
- Acidity: In acidic solutions, there is a greater concentration of H+ ions compared to hydroxide ions (OH-).
Ionic Compounds
- Dissolving in Water: Ionic compounds like sodium chloride (NaCl) dissociate due to the water lattice's polarity, separating Na+ from Cl- ions.
- Ionic Bonds: Formed from the electrical attractions between atoms that gain or lose valence electrons.
Elements and Compounds
- Trace Elements: Essential in small amounts, iodine is an example of a trace element.
- Living Organisms Composition: Composed mainly of 25 key elements, with a significant portion being CHON (carbon, hydrogen, oxygen, nitrogen).
- Other Important Elements: Calcium (Ca), phosphorus (P), potassium (K), sodium (Na), chlorine (Cl), magnesium (Mg), and sulfur (S) constitute about 4% of living matter.
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Test your understanding of key concepts in biology with these flashcards related to polar covalent bonds, buffers, lipid bilayers, and water's specific heat. Each card provides a definition to enhance your learning. Ideal for students prepping for exams or revising important topics.
