Questions and Answers
If an atom contains 3 protons, 4 neutrons, and 3 electrons, what is its mass number?
7
If an atom contains 11 protons and 12 neutrons, what is its atomic number?
11
What is a molecule of water made up of?
Two atoms of hydrogen and one atom of oxygen
How is a covalent bond formed?
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Why are water molecules polar?
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What do you produce when you stir salt into boiling water?
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What is a substance with a pH of 6 called?
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What are solutions that have more OH- than H+ ions called?
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Why is carbon considered special compared to other elements?
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How many covalent bonds can a carbon atom form?
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Match the following substances with their corresponding pairs:
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What happens to atoms in chemical reactions?
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When hydrogen atoms and oxygen atoms combine to form water, what is water considered?
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What are enzymes?
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Which subatomic particles are most involved in forming chemical bonds?
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Why is a water molecule polar?
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Match complex carbohydrates with their simple units:
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What are the elements or compounds that go into a chemical reaction called?
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What is the energy needed to start a chemical reaction?
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Can you predict the properties of a compound by knowing the properties of the elements that make up the compound?
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How does a sodium atom form a bond with a chlorine atom?
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What happens to atoms when H2 gas and O2 gas react to form water, and what kind of bonds result?
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What accounts for water's properties of adhesion and cohesion?
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What is a mixture?
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What relationship exists between the mass number of an element and its isotopes?
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When comparing tomato juice with a pH of 4 and soap with a pH of 10, what would you find regarding their acidity?
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How can you account for the great number, size, and complexity of organic compounds?
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Study Notes
Atomic Structure
- An atom's mass number is the sum of protons and neutrons; example: 3 protons and 4 neutrons give a mass number of 7.
- Atomic number reflects the number of protons; an atom with 11 protons has an atomic number of 11.
Molecular Composition
- Water consists of two hydrogen atoms and one oxygen atom, forming H2O.
- Covalent bonds are created when atoms share electrons.
Properties of Water
- Water molecules are polar, with the oxygen side being slightly negative and the hydrogen side slightly positive.
- The uneven distribution of electrons between oxygen and hydrogen creates the polar nature of water, leading to properties like adhesion and cohesion.
Solutions and pH
- Stirring salt into boiling water produces a solution, which is a homogeneous mixture.
- A substance with a pH of 6 is classified as an acid, while solutions with more OH- than H+ ions are considered bases.
- Tomato juice (pH 4) is acidic, and soap (pH 10) is basic; pH comparison indicates acid or base properties.
Organic Chemistry
- Carbon is unique due to its ability to form multiple bonds with itself and other elements, allowing various complex structures.
- Carbon-12, the most abundant isotope, has 6 protons, 6 neutrons, and 4 valence electrons, enabling it to form 4 covalent bonds.
Biological Macromolecules
- Amino acids are the building blocks of proteins, similar to how simple sugars serve as the foundation for starches.
- Complex carbohydrates consist of monosaccharides, just as polymers are composed of monomers.
Chemical Reactions
- In chemical reactions, atoms undergo rearrangement, transforming reactants into products such as water from hydrogen and oxygen.
- The activation energy is the necessary energy to initiate a chemical reaction.
Chemical Bonding
- Sodium forms an ionic bond with chlorine by losing an electron to become positively charged, while chlorine gains an electron to become negatively charged, resulting in ion attraction.
- When hydrogen and oxygen gases react, they rearrange into water molecules, forming covalent bonds between atoms.
Mixtures and Compounds
- Mixtures consist of two or more substances physically combined without chemical bonding, contrasting with pure compounds.
- Isotopes of an element share the same number of protons but differ in neutron count, resulting in varied mass numbers.
Laboratory Observations
- Organic compounds are numerous and complex due to carbon's ability to form diverse structures with multiple bonding possibilities.
- Enzymes work most effectively at specific pH levels and are proteins whose shape is crucial for function.
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Test your knowledge with these flashcards based on Chapter 2: The Chemistry of Life. Cover essential topics like atomic structure, molecular composition, and bond formation. Perfect for students looking to reinforce their understanding of chemistry concepts.