Matter and Atoms Overview

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Questions and Answers

What is the overall equation for photosynthesis?

6H2O + C6H12O6 → 6O2 + 6CO2

C6H12O6 + 6O2 → 6CO2 + 6H2O

6CO2 + 6O2 → 6H2O + C6H12O6

6CO2 + 6H2O → C6H12O6 + 6O2 (correct)

Which property of water allows it to support life by maintaining temperature?

Solvency

High heat of vaporization

High heat capacity (correct)

High surface tension

What type of bond forms between the oxygen atom of one water molecule and the hydrogen atom of another?

Nonpolar covalent bond

Hydrogen bond (correct)

Ionic bond

Polar covalent bond

What percentage of water content is typically found in all organisms?

70–90% Signup and view all the answers

Which of the following is NOT a property of water?

Magnetism Signup and view all the answers

What causes the atoms in a water molecule to share their electrons unequally?

Electronegativity of oxygen Signup and view all the answers

Which property of water is responsible for its ability to dissolve many substances?

Solvency Signup and view all the answers

What phenomenon allows water to form from hydrogen bonds?

Surface tension Signup and view all the answers

What is the maximum number of electrons that can occupy the second electron shell of an atom?

8 Signup and view all the answers

Carbon-14 dating can determine the age of organic materials up to approximately how many years?

60,000 years Signup and view all the answers

What happens to carbon-14 in an organism after it dies?

It changes into other atoms. Signup and view all the answers

Which of the following correctly describes valence in an atom?

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

The octet rule states that atoms are most stable when they have how many electrons in their outer shell?

8 Signup and view all the answers

What do orbitals represent in an atom?

The probable locations of electrons. Signup and view all the answers

In atoms with more than two shells, what is the primary factor affecting the stability of the outer shell?

Having a full outer shell of eight electrons. Signup and view all the answers

Which of the following statements about chemical properties of atoms is correct?

They are largely influenced by the arrangement of electrons. Signup and view all the answers

What property of water allows it to dissolve many substances?

Polarity and hydrogen bonding Signup and view all the answers

Which type of molecules are attracted to water?

Hydrophilic Signup and view all the answers

How does water's adhesion property assist in nature?

It helps in the transportation of water within plants. Signup and view all the answers

What occurs when NaCl is dissolved in water?

The salt dissociates into ions. Signup and view all the answers

What contributes to the high surface tension of water?

Hydrogen bonding between water molecules Signup and view all the answers

Which property of water explains why it moves up a tree from the roots to the leaves?

Cohesion Signup and view all the answers

Hydrophobic molecules are characterized by their ability to:

Repel water. Signup and view all the answers

What is the general process by which molecules separate into ions, atoms, or radicals called?

Dissociation Signup and view all the answers

What property of water allows it to absorb heat without significantly changing temperature?

Hydrogen bonding Signup and view all the answers

What happens to the temperature of water when it absorbs heat?

It rises and falls slowly Signup and view all the answers

Why does ice float on water?

Water expands as it freezes, making ice less dense Signup and view all the answers

What energy change occurs as water evaporates?

Cooling occurs due to heat dispersion Signup and view all the answers

What role does ice play in aquatic environments?

It acts as a thermal insulator Signup and view all the answers

What is the primary function of buffers in the body?

To keep pH within normal limits by neutralizing excess H+ and OH- Signup and view all the answers

What is the normal pH range of blood in a healthy individual?

7.35 – 7.45 Signup and view all the answers

What condition can result from the body's inability to buffer excess H+ ions?

Acidosis Signup and view all the answers

Which disease is associated with an increased risk of acidosis due to buffering failure?

Congestive heart failure Signup and view all the answers

What can ultimately happen if acidosis is left untreated?

Organ failure and death Signup and view all the answers

What ions are produced when water dissociates?

Hydrogen ions and hydroxide ions Signup and view all the answers

Which solution is considered acidic based on pH?

pH of 5 Signup and view all the answers

Which of the following acids releases hydrogen ions when dissolved?

Hydrochloric acid Signup and view all the answers

A solution with a pH of 6 is classified as what?

Acidic Signup and view all the answers

What happens to the concentration of hydroxide ions in a basic solution?

It is higher than that of hydrogen ions Signup and view all the answers

Which of the following describes the pH scale?

Ranges from 0 to 14 Signup and view all the answers

Which solution is classified as basic?

Milk of magnesia Signup and view all the answers

What does a pH of 7 indicate about a solution?

It is neutral with equal H+ and OH− ions Signup and view all the answers

Study Notes

Matter and Atoms

Matter is anything that occupies space and has mass.
Matter exists as solids, liquids, gases, or plasma.
Matter is composed of elements.
An element cannot be broken down into other substances by ordinary chemical means.
Only 92 elements occur naturally.
Four elements—carbon, hydrogen, oxygen, and nitrogen—make up about 96% of the body weight of most living organisms.

Where Elements Come From

Normal chemical reactions do not produce elements.
Heavier elements, like iron, are created in supernova explosions.
Supernova explosions scatter heavier elements into space, which then become parts of planets.

Atomic Structure 1

Atoms are the basic units of elements.
Atoms cannot be subdivided into smaller substances without losing their properties.
Atoms are composed of subatomic particles:
- Protons (positively charged)
- Neutrons (no charge)
- Electrons (negatively charged)
Protons and neutrons are found in the nucleus.
Electrons are found outside the nucleus in orbitals.

Atomic Structure 2

Atomic symbol: represents the atom/element
Examples: H (hydrogen), Na (sodium)
Mass number: sum of protons and neutrons (electrons have negligible mass)

Atomic Number

All atoms of an element have the same number of protons.
The atomic number equals the number of protons and electrons in a neutral atom.

Periodic Table

Elements' chemical and physical characteristics recur in a predictable manner.
Elements are arranged in periods (rows) and groups (columns) in the periodic table.

Isotopes

Atoms of the same element can differ in the number of neutrons.
Isotopes have the same number of protons but different numbers of neutrons (and thus different mass numbers).
Some isotopes are unstable and decay, emitting radiation.
Radioactive isotopes behave very similarly to stable isotopes, but can be used as tracers or to sterilize equipment.

Arrangement of Electrons in an Atom

Electrons are constantly moving.
Electron shells are useful for models of atoms with energy levels.
Each shell contains a certain number of electrons.
Orbitals are pathways in which electrons rotate around the nucleus.

Bonds and Molecules

Molecules result from combinations of two or more atoms.
Compounds are molecules composed of two or more different elements.
Atoms can share, donate, or accept electrons to form chemical bonds.

Types of Chemical Bonds

Chemical bonds form when two or more atoms share, donate, or accept electrons.
- Ionic bonds: result from electron transfers between atoms, forming ions with opposite charges.
- Covalent bonds: result from electron sharing between atoms to complete their outer electron shells.
- Hydrogen bonds: occur when a hydrogen atom attracted to electronegative atoms (like oxygen or nitrogen).

Chemical Formulas and Reactions

Chemical formulas show the elements and the relative number of atoms in a compound.
Balanced chemical equations have the same number of each type of atom on both sides.
Reactants are substances that participate in a chemical reaction.
Products are the substances produced by a chemical reaction.

Water's Importance to Life

Life began in water.
Water is the most important molecule on Earth, making up 70-90% of most organisms.
Water's properties (solvency, cohesion, adhesion, high surface tension, high heat capacity, high heat of vaporization, and varying density) are crucial for life.

Acids and Bases

Water dissociates into hydrogen ions (H⁺) and hydroxide ions (OH⁻).
Acidic solutions have a high concentration of H⁺ ions, while basic solutions have a low concentration of them and a high concentration of OH⁻.
The pH scale measures the concentration of H⁺ ions in a solution.
Buffers are substances that maintain a relatively stable pH.

pH and pH Scale

pH is the scale used to measure hydrogen ion concentration.
The pH scale ranges from 0 to 14, with 7 being neutral.
An acidic solution has a low pH, while an alkaline (basic) solution has a high pH.

Buffers and pH

Buffers resist changes in pH by absorbing or releasing H+ or OH- ions.
The human body uses buffers to maintain a relatively constant blood pH.

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Description

Explore the fundamental concepts of matter and atoms in this quiz. Learn how elements combine to form matter and the origins of elements in the universe. Test your understanding of atomic structure and the role of subatomic particles.