Atomic Structures and Electron Shells

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Questions and Answers

What is the primary reason elements tend to lose, gain, or share electrons?

To satisfy the octet rule (correct)

To form ionic bonds

To create molecular compounds

To become cations

What do you call the outer electron shell of an atom?

Electron cloud

Valence shell (correct)

Core shell

Nucleus

Which of the following molecules is an example of a covalent compound?

NaOH

H2O (correct)

KCl

NaCl

How many electrons can the second orbit of an atom hold?

8 electrons Signup and view all the answers

What charge do ions carry?

Can be positive or negative Signup and view all the answers

Which type of bond involves the sharing of electrons?

Covalent bond Signup and view all the answers

What characterizes a polar covalent bond?

Uneven sharing of electrons Signup and view all the answers

What is required for a molecule to be classified as a molecular compound?

Two or more elements with covalent bonds Signup and view all the answers

What characteristic of water allows structures like the alveoli to remain open and not collapse?

Water’s high surface tension Signup and view all the answers

Which type of substance does not dissolve in water and remains intact?

Nonelectrolytes Signup and view all the answers

What property of amphipathic molecules allows them to form cell membranes?

Their hydrophobic and hydrophilic portions Signup and view all the answers

Which of the following statements about water is incorrect?

Water does not lubricate effectively. Signup and view all the answers

What role do surfactants play in the lungs?

They reduce surface tension. Signup and view all the answers

When body fluids are altered in pH, which substance is commonly added to create acidity?

Acids Signup and view all the answers

Which of the following best describes hydrophobic molecules?

They are excluded by water molecules. Signup and view all the answers

How do electrolytes behave when mixed with water?

They dissolve and dissociate into ions. Signup and view all the answers

What phenomenon is primarily responsible for the collapse of moist sacs of air in the lungs?

Surface tension Signup and view all the answers

Which property of water primarily contributes to maintaining a stable body temperature?

High specific heat Signup and view all the answers

What is the function of surfactant in the lungs?

It lowers surface tension. Signup and view all the answers

How does water's high heat of vaporization benefit the human body?

It aids in cooling the body. Signup and view all the answers

Which characteristic of water allows it to effectively transport substances in body fluids?

Ability to dissolve various substances Signup and view all the answers

What enables water to attach to blood vessels, preventing gaps or air pockets?

Adhesion Signup and view all the answers

Which of the following explains why water has a high specific heat?

It requires energy to break hydrogen bonds. Signup and view all the answers

What role does cerebrospinal fluid serve in the body?

It cushions the brain against movements. Signup and view all the answers

How many ATP are produced per glucose during the entire cellular respiration process?

38 ATP Signup and view all the answers

What is the primary role of the protein complexes in the Electron Transport System?

To create a concentration gradient for H+ ions Signup and view all the answers

During the Citric Acid Cycle, how many molecules of NADH are produced from one glucose?

6 NADH Signup and view all the answers

What happens to H+ ions in the Electron Transport System?

They create a gradient and combine with O2 to form water. Signup and view all the answers

What effect does ATP have on the enzymes involved in cellular respiration?

ATP acts as an inhibitor to many enzymes. Signup and view all the answers

What is produced in the intermediate step of cellular respiration before entering the Citric Acid Cycle?

2 NADH and CO2 Signup and view all the answers

Which of the following correctly describes the relationship between GTP and ATP during the Citric Acid Cycle?

GTP is produced instead of ATP. Signup and view all the answers

In the Citric Acid Cycle, how many carbon dioxide molecules are released per cycle?

2 CO2 Signup and view all the answers

What is the role of RNA in protein synthesis?

Is read to make proteins Signup and view all the answers

Which of the following components is found in RNA but not in DNA?

Ribose sugar Signup and view all the answers

Which type of reaction involves the breaking down of substances into smaller components?

Decomposition reaction Signup and view all the answers

How do exergonic reactions differ from endergonic reactions?

Exergonic reactions release energy while endergonic reactions store energy. Signup and view all the answers

What is the primary function of enzymes in the body?

To act as catalysts that accelerate reactions Signup and view all the answers

What is a defining characteristic of the active site of an enzyme?

It has a unique 3-dimensional structure. Signup and view all the answers

Which statement about metabolic reactions in the human body is TRUE?

Water serves as a solvent where reactions occur. Signup and view all the answers

What suffix indicates that a substance is likely an enzyme?

-ase Signup and view all the answers

Study Notes

Atomic Structure and Chemical Bonds

Atoms have electron "shells" surrounding the nucleus, with each shell having a specific electron capacity.
The first shell can hold 2 electrons, while the second and third shells can accommodate 8 electrons each.
Valence shells desire to be full, leading to chemical stability.
The octet rule explains that atoms tend to lose, gain, or share electrons to attain full outer shells.

Chemical Compounds and Bonds

Chemical compounds consist of stable combinations of two or more elements in fixed ratios, typically satisfying the octet rule.
Two main types of chemical bonds form these compounds: ionic and covalent bonds.
Ionic compounds are structured around ions, which are charged atoms resulting from the loss or gain of electrons.

Ions and Their Functions

Cations are positive ions (e.g., Na+, K+), while anions are negative (e.g., Cl-, PO3-).
Ions act as electrolytes, dissociating in water and conducting electrical currents.

Covalent Bonding

Covalent bonds occur when atoms share electrons from their outermost shells.
Molecular compounds consist of two or more atoms linked by covalent bonds (e.g., CO2) while molecular oxygen (O2) is simply termed a molecule.
Covalent bonds can be single (one pair of electrons shared), double (two pairs), or triple (three pairs).

Properties of Water

Water is essential for life; it has high specific heat and high heat of vaporization, stabilizing body temperature.
High specific heat prevents drastic temperature changes, while high heat of vaporization allows the body to cool effectively through sweating.
Water’s high surface tension helps prevent lung alveoli from collapsing and provides lubrication in various body systems.

pH and Biological Relevance

Water has a neutral pH, but body fluids can vary with the addition of acids or bases.
The pH range in the body is generally around 7.0-7.4, with exceptions in specific organs.

Nucleic Acids and Their Functions

Nucleotides, the building blocks of nucleic acids, consist of a 5-carbon sugar, phosphate group, and nitrogenous base.
DNA stores and transmits hereditary information, while RNA is critical for protein synthesis.

Energy and Metabolism

Water, comprising around 60% of the body, serves as a solvent for biochemical reactions.
Body temperature (98.6°F or 37°C) and a stable pH of 7.0-7.4 enable efficient enzymatic reactions.

Types of Chemical Reactions

Decomposition reactions break down compounds into simpler structures (AB → A + B).
Synthesis reactions combine structures to form larger entities (A + B → AB).
Exchange reactions involve swapping groups between chemical structures (AB + C → A + BC).

Enzymes and Their Role

Enzymes are globular proteins that act as catalysts, increasing reaction rates without altering the equilibrium.
Enzymes have specific active sites that accommodate particular substrates, facilitating precise biochemical reactions.

Cellular Respiration

Cellular respiration includes glycolysis, the citric acid cycle, and the electron transport chain.
ATP production totals approximately 38 molecules per glucose, with glycolysis and the electron transport chain contributing significantly to ATP yield.
ATP also serves as a regulatory molecule, inhibiting various enzymes during cellular respiration through negative feedback.

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Description

This quiz covers the fundamental concepts of atomic structures, focusing on the arrangement of electrons in shells around the nucleus. It includes topics such as the capacity of each shell, the importance of filling inner shells first, and the significance of valence shells in chemical stability according to the octet rule.