Chemistry of Life Chapter 2
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Questions and Answers

What is the maximum number of electrons the second and third energy levels can hold?

  • 8 electrons (correct)
  • 6 electrons
  • 10 electrons
  • 4 electrons

What is formed when an atom loses electrons?

  • An anion
  • A cation (correct)
  • A neutral atom
  • A free radical

Which element has only one electron in its outermost shell?

  • Lithium (correct)
  • Fluorine
  • Beryllium
  • Neon

What is meant by the octet rule?

<p>Atoms are most stable with a filled outer shell of eight electrons. (B)</p> Signup and view all the answers

Why does sodium prefer to lose one electron rather than gain seven?

<p>It takes less energy to lose an electron than to gain seven. (C)</p> Signup and view all the answers

What charge does a chloride ion have after it gains an electron?

<p>-1 (D)</p> Signup and view all the answers

What happens when an atom has an unequal number of protons and electrons?

<p>It is considered an ion. (D)</p> Signup and view all the answers

What happens to the concentration of Carbon-14 in an organism after it dies?

<p>It begins to decline. (D)</p> Signup and view all the answers

Why do chemical bonds form between elements?

<p>To fill vacancies in the outermost shells. (D)</p> Signup and view all the answers

Which statement best describes the process of electron transfer?

<p>It forms an ionic bond between atoms. (D)</p> Signup and view all the answers

How many elements are found in the first row of the periodic table?

<p>Two elements (A)</p> Signup and view all the answers

What is the process called when Carbon-14 decays to Nitrogen-14?

<p>Beta decay (D)</p> Signup and view all the answers

In the formation of ionic bonds, why do positive and negative ions attract each other?

<p>They have opposite charges. (C)</p> Signup and view all the answers

What is the arrangement of electrons in higher energy levels?

<p>In single positions before pairing. (A)</p> Signup and view all the answers

How long is the half-life of Carbon-14?

<p>5,730 years (B)</p> Signup and view all the answers

What defines an ionic bond?

<p>A bond formed by transferring electrons. (D)</p> Signup and view all the answers

What is the maximum age limit for objects that can be dated using Carbon-14?

<p>50,000 years (A)</p> Signup and view all the answers

Which ion is formed from sodium after losing an electron?

<p>Sodium ion (D)</p> Signup and view all the answers

Which element completes its outer shell with eight electrons?

<p>Neon (B)</p> Signup and view all the answers

Which of the following isotopes is typically used for dating older fossils than those dated by Carbon-14?

<p>Potassium-40 (B)</p> Signup and view all the answers

How many electrons does a chlorine atom have after gaining one electron?

<p>18 (C)</p> Signup and view all the answers

Which shell around the atom's nucleus is filled first with electrons?

<p>Closest shell (A)</p> Signup and view all the answers

How many electrons can the closest shell to the nucleus hold?

<p>2 electrons (C)</p> Signup and view all the answers

What determines how elements interact with one another?

<p>Arrangement of electrons (B)</p> Signup and view all the answers

What type of bond forms when an electron is shared between two elements?

<p>Covalent bond (D)</p> Signup and view all the answers

Which characteristic distinguishes covalent bonds from ionic bonds in the context of water?

<p>Covalent bonds do not dissociate in water (D)</p> Signup and view all the answers

How many shared electrons are needed for two nitrogen atoms to fill their outermost shells?

<p>Three (A)</p> Signup and view all the answers

What type of covalent bond occurs when electrons are shared equally between atoms?

<p>Nonpolar covalent bond (C)</p> Signup and view all the answers

In methane (CH4), how many electrons does the carbon atom share with hydrogen atoms?

<p>Four (B)</p> Signup and view all the answers

What is the bond type between two oxygen atoms forming oxygen gas (O2)?

<p>Double covalent bond (B)</p> Signup and view all the answers

What is formed as a result of ionic bonding between sodium and chloride ions?

<p>Crystal lattice structure (B)</p> Signup and view all the answers

Which statement correctly describes polar covalent bonds?

<p>They have unequal sharing of electrons. (A)</p> Signup and view all the answers

What is indicated by the unequal distribution of electrons in a polar covalent bond?

<p>Partial positive and negative charges develop (D)</p> Signup and view all the answers

In a water molecule, which atom carries a slightly negative charge?

<p>Oxygen atom (A)</p> Signup and view all the answers

What primarily causes the formation of hydrogen bonds in water?

<p>Attraction between δ+ and δ– charges (A)</p> Signup and view all the answers

Which statement best describes the relationship between polar covalent bonds and the properties of water?

<p>Polar covalent bonds lead to the liquid state of water (B)</p> Signup and view all the answers

What type of bonds are weaker compared to ionic and covalent bonds?

<p>Hydrogen bonds (C)</p> Signup and view all the answers

What change would occur to water if hydrogen bonding did not exist?

<p>Water would become a gas at room temperature (D)</p> Signup and view all the answers

Which molecule is an example of a nonpolar bond?

<p>Methane (A)</p> Signup and view all the answers

What does the δ+ symbol represent in polar covalent bonding?

<p>A partial positive charge (C)</p> Signup and view all the answers

What percentage of the human body is primarily composed of water?

<p>60–70 percent (A)</p> Signup and view all the answers

What is the main reason that water is critical to life as we know it?

<p>It is abundant in living cells. (A)</p> Signup and view all the answers

Which statement best describes why water behaves as a polar molecule?

<p>Shared electrons are more associated with the oxygen atom. (A)</p> Signup and view all the answers

What term is used to describe substances that do not mix with water?

<p>Hydrophobic (A)</p> Signup and view all the answers

How do hydrogen bonds in water affect its temperature stability?

<p>They allow water to absorb and release heat slowly. (C)</p> Signup and view all the answers

Which description correctly defines water's ability to moderate temperature changes?

<p>Water can absorb large amounts of energy with minimal temperature changes. (D)</p> Signup and view all the answers

What phenomenon causes the unique shape of water molecules?

<p>The arrangement of hydrogen and oxygen atoms. (D)</p> Signup and view all the answers

Why are substances that easily form hydrogen bonds with water said to be hydrophilic?

<p>They can dissolve in water. (A)</p> Signup and view all the answers

Flashcards

Carbon-14

A naturally occurring radioisotope created in the atmosphere by cosmic rays, used for carbon dating.

Radioisotope

An unstable isotope of an element that decays over time.

Carbon Dating

A method to determine the age of formerly living objects, estimating how long an organism has been dead.

Half-life

The time needed for half of a radioactive sample to decay.

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Beta Decay

The process by which carbon-14 decays to nitrogen-14.

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Fossil Age Range (Carbon-14)

Carbon-14 dating can estimate the age of fossils up to approximately 50,000 years old.

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Isotope

Atoms of the same element with different numbers of neutrons.

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Electron Shells

Energy levels where electrons orbit the nucleus of an atom.

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Electron Shell Capacity

The maximum number of electrons that can be held in a particular electron shell.

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Octet Rule

Atoms tend to gain, lose, or share electrons to achieve a full outer electron shell containing eight electrons.

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First Electron Shell

The lowest energy level electron shell. It can hold a maximum of two electrons.

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Second and Third Electron Shells

Electron shells that can hold up to eight electrons each.

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Periodic Table Rows

Rows on the periodic table indicating the number of electron shells for the elements in that row.

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Chemical Bonds

Interactions between atoms resulting in the formation of molecules.

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Ions

Atoms that have gained or lost electrons, thus having an unequal number of protons and electrons, resulting in a net electrical charge.

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Ionic bond

A strong bond formed between oppositely charged ions.

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Cation

A positively charged ion formed by losing electrons.

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Electron transfer

Movement of electrons from one element to another during ionic bond formation.

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Sodium ion

A positively charged ion formed when a sodium atom loses an electron.

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Chloride ion

A negatively charged ion formed when a chlorine atom gains an electron.

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Ionic Compound

A compound that forms from the attraction between positive and negative ions.

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Covalent Bond

A bond where atoms share electrons to achieve a stable outer electron shell.

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Nonpolar Covalent Bond

A covalent bond where electrons are shared equally between atoms.

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Polar Covalent Bond

A covalent bond where electrons are shared unequally, creating partial positive and negative charges on the atoms.

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What makes a covalent bond strong?

Covalent bonds are strong because the shared electrons create a stable configuration in the outer electron shells of the atoms.

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How many covalent bonds form?

The number of covalent bonds an atom can form depends on how many electrons it needs to fill its outer shell.

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Why do atoms form bonds?

Atoms form bonds to achieve a stable electron configuration, usually by filling their outer electron shell, resulting in lower energy.

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Different types of bonds in water

Water molecules (H2O) are formed by polar covalent bonds between hydrogen and oxygen atoms, and the attraction between water molecules results from weak hydrogen bonds.

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Water's Polarity

Water molecules have a slight positive charge on the hydrogen atoms and a slight negative charge on the oxygen atom due to unequal sharing of electrons.

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Hydrogen Bonding

Attraction between slightly positive hydrogen atoms of one water molecule and slightly negative oxygen atoms of another water molecule.

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Hydrophilic

Substances that readily dissolve in water due to their ability to form hydrogen bonds with water molecules.

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Hydrophobic

Substances that do not dissolve in water because they cannot form hydrogen bonds.

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Water's Role in Temperature Regulation

Water's hydrogen bonds help it absorb and release heat energy slowly, stabilizing temperature changes within organisms and their environments.

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How Hydrogen Bonds Affect Heat Absorption

Breaking hydrogen bonds requires energy. Water absorbs this energy before its temperature rises significantly.

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Water's Importance for Life

Water is essential for life, making up a large percentage of living organisms. It's involved in many biological processes and helps regulate temperature.

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What Makes Water Unique?

Water's unique properties, like its polarity and ability to form hydrogen bonds, are essential for its role in supporting life.

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What makes water polar?

Water molecules have polar covalent bonds between hydrogen and oxygen, where the oxygen atom is more electronegative, pulling electrons towards itself.

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Why is hydrogen bonding important?

Hydrogen bonds give water unique properties like liquid state at room temperature and the ability to dissolve many substances.

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Van der Waals Interactions

Weak attractions between temporary fluctuations of electron density in molecules.

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Compare ionic and covalent bonds

Ionic bonds involve the transfer of electrons, forming ions with opposite charges. Covalent bonds involve the sharing of electrons.

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Nonpolar bond

A covalent bond where electrons are shared equally, resulting in no charge separation.

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Why are weak bonds important?

Weak bonds like hydrogen bonds and van der Waals interactions help stabilize biological molecules and structures, like DNA and protein.

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Study Notes

Chapter 2: Chemistry of Life

  • Matter occupies space and has mass
  • Elements are substances that cannot be broken down chemically
  • Each element is made of atoms with a constant number of protons and unique properties
  • 118 elements are defined naturally, only 92 occur and fewer than 30 are found in living cells

2.1 The Building Blocks of Molecules

  • Atoms are the fundamental unit of an element.
  • Atoms are composed of protons (positive charge, mass of 1), neutrons (neutral charge, mass of 1), and electrons (negative charge, negligible mass) located in shells around the nucleus.

Atomic Structure

  • Protons and neutrons are in the nucleus
  • Electrons are outside the nucleus in electron shells
  • Atoms are electrically neutral because the number of protons equals the number of electrons
  • Isotopes are different forms of the same element with the same number of protons but a different number of neutrons

Chemical Bonding

  • Elements combine to form molecules through chemical bonds.
  • Ionic bonds form between oppositely charged ions by electron transfer
  • Covalent bonds form when atoms share electrons, creating molecules
  • Polar covalent bonds result when electrons are unequally shared, causing a partial positive charge and a negative charge in the molecule
  • Nonpolar covalent bonds result when electrons are shared equally between elements
  • Hydrogen bonds are weak bonds between a hydrogen atom and an electronegative atom.
  • van der Waals interactions are weak interactions between molecules.

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Chapter 2 Chemistry of Life PDF

Description

Explore the fundamental concepts in Chapter 2 of Chemistry of Life. This quiz covers matter, elements, atomic structure, and chemical bonding, helping you understand how atoms interact to form molecules. Test your knowledge on the building blocks of life!

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