Biology Chapter 2: The Chemical Context of Life

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Questions and Answers

What is the significance of emergent properties in biological systems?

They show that compounds are less complex than their individual elements.

They indicate that all elements behave similarly when combined.

They demonstrate how characteristics change when elements combine to form compounds. (correct)

They arise only at the atomic level of organization.

Which statement accurately describes the nature of elements?

Elements can be divided into smaller parts through chemical reactions.

Each element has a unique atomic number that reflects its mass.

Elements cannot be broken down into other substances by chemical reactions. (correct)

There are more than 200 naturally occurring elements on Earth.

What percentage of an organism's weight do the four primary elements constitute?

About 60%

Roughly 96% (correct)

Close to 50%

Approximately 75%

Which of the following is classified as a trace element?

Iron (Fe) Signup and view all the answers

What is the role of compounds in living organisms?

They provide new properties that are not present in their constituent elements. Signup and view all the answers

Which statement accurately describes the relationship between an atom's nucleus and its electrons?

Electrons orbit the nucleus at varying distances, affecting their potential energy. Signup and view all the answers

What happens to electrons during a chemical reaction between two elements?

Only the electrons are involved in the interaction. Signup and view all the answers

How does the potential energy of an electron change as its distance from the nucleus increases?

It increases because the electron is less negatively influenced by the nucleus. Signup and view all the answers

What defines the different states of potential energy for electrons in an atom?

Electron shells, which correspond to fixed locations around the nucleus. Signup and view all the answers

What is the consequence of an electron absorbing energy in regards to its position relative to the nucleus?

It may move to a higher energy shell or level. Signup and view all the answers

What role do unpaired electrons play in atomic interactions?

They are involved in completing valence shells during interactions. Signup and view all the answers

Which of the following describes a covalent bond?

A bond involving the sharing of two pairs of electrons between atoms. Signup and view all the answers

What is indicated by the molecular formula H2?

It indicates two bonded hydrogen atoms forming a molecule. Signup and view all the answers

How many covalent bonds can an oxygen atom typically form?

Two bonds, as it needs to share two more electrons to complete its valence shell. Signup and view all the answers

What defines an atom's valence?

The number of unpaired electrons in its outermost shell. Signup and view all the answers

What is the function of the mass number in relation to an atom?

It indicates the total number of particles in the nucleus of an atom. Signup and view all the answers

How can one determine the number of neutrons in an atom?

By subtracting the atomic number from the mass number. Signup and view all the answers

Which statement correctly defines isotopes?

Atoms of the same element that differ in the number of neutrons. Signup and view all the answers

What is a common application of radioactive isotopes in biological research?

Tracing atoms through metabolic processes. Signup and view all the answers

What type of isotopes are typically used in medical diagnostics?

Radioactive isotopes that decay and emit particles. Signup and view all the answers

Study Notes

Chapter 2: The Chemical Context of Life

Living organisms are subject to the laws of physics and chemistry.
Biology is a multidisciplinary science.
Life is organized into a hierarchy of structural levels: atoms, molecules, cells, etc.
Elements are substances that cannot be broken down.
There are 92 naturally occurring elements.
Each element has a unique symbol.
A compound is a substance made of two or more elements in a fixed ratio (e.g., NaCl).
The properties of a compound differ from those of its constituent elements.

Concept 2.1: Matter and Elements

Matter is anything that takes up space and has mass.
Matter is made of elements.
Elements are made of atoms.
Atoms consist of subatomic particles (protons, neutrons, electrons).

Concept 2.2: Atomic Structure

Atoms are mostly empty space.
Atomic nucleus contains protons and neutrons.
Electrons surround the nucleus.
Mass of a proton or neutron is close to 1 dalton.
Mass of an electron is about 1/2000th of a proton or neutron.
Atoms have equal numbers of protons and electrons, thus no net charge.
Atomic number is the number of protons in an atom's nucleus.
Isotopes are atoms of the same element that differ in the number of neutrons.
Radioactive isotopes are unstable; they spontaneously decay, emitting particles and energy.
Mass number is the sum of protons and neutrons in an atom's nucleus.
Atomic mass is the average mass of an atom's isotopes.

Electron Configuration

Electrons occupy energy levels (shells) around the nucleus.
The first shell holds a maximum of 2 electrons.
Higher shells can hold more electrons than the first shell.
The chemical behaviour of an atom is determined by its electron configuration.
Valence electrons are those in the outermost shell.
Atoms with complete valence shells are unreactive (inert).
Valence refers to the number of unpaired electrons in the outermost shell of an atom.

Concept 2.3: Chemical Bonding

Atoms with incomplete valence shells interact with each other through sharing or transferring valence electrons.
Covalent bonds form when atoms share one or more pairs of valence electrons.
Ionic bonds form when one atom completely transfers an electron to another, creating ions.
Hydrogen bonds involve an attraction between a hydrogen atom with a partial positive charge and an electronegative atom.
Van der Waals interactions are weak, fleeting attractions occurring between temporarily positive and negative regions of molecules.

Concept 2.4: Chemical Reactions

Chemical reactions make and break chemical bonds.
Reactants are the starting molecules in a reaction; products are the resulting molecules.
Matter is conserved in chemical reactions. Chemical reactions do not create or destroy matter.
Some reactions go to completion but others reach a state of equilibrium. Equilibrium is reached when the rate of product formation equals the rate of reactant formation.

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Description

Explore the fundamental concepts of chemistry that underpin biological processes in this quiz focused on Chapter 2. Learn about matter, elements, and atomic structure, and discover how they relate to the organization of life. This quiz will test your understanding of these foundational topics in biology.