Chemistry Basics Quiz

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Questions and Answers

What is the atomic mass of an element with 11 protons and 12 neutrons?

23 (correct)

Which of these is NOT a component of an atom?

Electron

Proton

Neutron

Nucleus (correct)

What is the charge of a proton?

+1 (correct)

-1

What is the name of the element with the symbol 'Na'?

Sodium (D) Signup and view all the answers

How many electrons does a neutral atom of oxygen have?

8 (B) Signup and view all the answers

Which element is the most abundant in the human body?

Oxygen (B) Signup and view all the answers

What is the primary difference between isotopes of the same element?

Number of neutrons (A) Signup and view all the answers

What is the relationship between an element's atomic number and its number of protons?

The atomic number is equal to the number of protons. (A) Signup and view all the answers

Which of the following accurately describes the relationship between the concentration of hydrogen ions (H+) and the pH value of a solution?

As H+ concentration decreases, pH increases. (B) Signup and view all the answers

Which of the following is a characteristic of a weak base?

It has a very low tendency to absorb H+ ions, resulting in a minimal decrease in free H+ concentration. (B) Signup and view all the answers

What is the pH of a neutral solution, and why is it considered neutral?

pH 7, because it contains equal concentrations of H+ and OH- ions. (C) Signup and view all the answers

Which of the following statements accurately describes a buffer system within the body?

It neutralizes excess acid or base, maintaining a stable pH. (B) Signup and view all the answers

What happens to the pH of a solution when a strong acid is added?

The pH decreases significantly. (C) Signup and view all the answers

Which of the following accurately describes a suspension as a water mixture type?

Larger particles that settle out if left undisturbed. (B) Signup and view all the answers

If the pH of a solution is 6, how does the concentration of H+ ions compare to that of pure water?

It is 10 times higher. (A) Signup and view all the answers

Which of the following examples best demonstrates the process of neutralization?

Taking an antacid tablet to alleviate heartburn. (C) Signup and view all the answers

Which of the following statements accurately describes the relationship between electronegativity and bond polarity?

The greater the electronegativity difference between two atoms, the more polar the covalent bond. (D) Signup and view all the answers

Which of the following is an example of a nonpolar molecule containing polar covalent bonds?

Carbon dioxide (CO2) (C) Signup and view all the answers

Which of the following statements correctly describes a hydrogen bond?

A hydrogen bond is a weak attraction between the positively charged end of a molecule and the negatively charged end of another molecule. (B) Signup and view all the answers

Which of the following molecules can form hydrogen bonds?

Water (H2O) (D) Signup and view all the answers

Which of the following is NOT a property of amphipathic molecules?

They are always soluble in water. (A) Signup and view all the answers

Which of the following statements correctly explains why water is a neutral solvent?

Water molecules dissociate into equal numbers of hydrogen ions (H+) and hydroxide ions (OH-), maintaining a neutral pH. (A) Signup and view all the answers

Which of the following elements has the highest electronegativity?

Oxygen (O) (B) Signup and view all the answers

Which of the following bonds is considered nonpolar?

C - H (D) Signup and view all the answers

What is the term used to describe substances that dissolve in water and conduct electricity?

Electrolytes (D) Signup and view all the answers

Which of the following best describes the function of sweating in relation to body temperature?

Sweating cools the body by dissipating excess heat through evaporation. (B) Signup and view all the answers

What characteristic do amphipathic molecules possess?

They have both polar and nonpolar regions. (B) Signup and view all the answers

How do nonpolar molecules interact with water?

They are forced out by cohesive water molecules. (D) Signup and view all the answers

Which statement accurately describes water's role as a universal solvent?

Most polar molecules and ions can dissolve in water. (A) Signup and view all the answers

What is the charge of an ion that has 12 protons and 10 electrons?

+2 (D) Signup and view all the answers

Which of the following is NOT a characteristic of an ionic bond?

Involves the sharing of electrons (A) Signup and view all the answers

What type of chemical bond is present in a molecule of carbon dioxide (CO₂)?

Covalent bond (B) Signup and view all the answers

How many covalent bonds can a nitrogen atom typically form?

3 (C) Signup and view all the answers

Which of the following best describes a double covalent bond?

Two pairs of electrons are shared between two atoms. (A) Signup and view all the answers

Which of the following is an example of a polyatomic ion?

Bicarbonate ion (HCO₃⁻) (B) Signup and view all the answers

Which of the following is an example of a molecular compound?

Carbon dioxide (CO₂) (D) Signup and view all the answers

What is the difference between a structural formula and a molecular formula?

The structural formula shows the arrangement of atoms in a molecule, while the molecular formula only indicates the number and type of atoms. (D) Signup and view all the answers

Which of the following best describes a colloid?

Mixture with particles larger than in a solution but smaller than in a suspension. (D) Signup and view all the answers

What characteristic distinguishes a solution from other types of mixtures?

It does not scatter light and remains homogeneous. (A) Signup and view all the answers

What functions does liquid water serve in the human body?

It lubricates and cushions body structures. (B) Signup and view all the answers

What allows water to have a high specific heat?

The energy needed to break hydrogen bonds. (A) Signup and view all the answers

What is the role of a surfactant in relation to water's surface tension?

To prevent the collapse of moist sacs of air in lungs. (A) Signup and view all the answers

How do hydrophilic and hydrophobic molecules differ in their interaction with water?

Hydrophilic molecules dissolve in water, whereas hydrophobic do not. (B) Signup and view all the answers

Which of these phases is not a standard phase of water?

Solid gel (A) Signup and view all the answers

What is the primary effect of cohesion in water molecules?

It creates surface tension and affects interactions with other surfaces. (C) Signup and view all the answers

Study Notes

Matter, Atoms, Elements, and the Periodic Table

Matter has mass and occupies space
Three forms of matter: solid, liquid, gas
Atom is the smallest particle exhibiting chemical properties of an element.
92 naturally occurring elements make up matter
Elements are organized in the periodic table.

Most Common Elements in the Human Body

Oxygen (O): 65.5%
Carbon (C): 18.5%
Hydrogen (H): 9.5%
Nitrogen (N): 3.0%
Calcium (Ca): 1.5%
Phosphorus (P): 1.0%
Other minor elements are less than 1%

Components of an Atom

Atoms are composed of three subatomic particles: neutrons, protons, and electrons
Neutrons:
- Have a mass of one atomic mass unit (amu)
- Have no charge
- Located in the nucleus
Protons:
- Have a mass of one amu
- Have a positive charge (+1)
- Located in the nucleus
Electrons:
- Have 1/1800th the mass of a proton or neutron
- Have a negative charge (-1)
- Located at varying distances from the nucleus in regions called orbitals or shells

Periodic Table

Chemical symbol: unique to each element
Usually identified by the first letter or first letter plus another letter
Atomic number: number of protons in an atom
Located above the element symbol
Average atomic mass: shown below the element symbol on the table
Elements are arranged by atomic number in rows.

Determining the Number of Subatomic Particles

Proton number = atomic number
Neutron number = atomic mass - atomic number
Electron number = proton number

Diagramming Atomic Structures

An atom has electron "shells" surrounding the nucleus
Each shell has a specific energy level
The innermost shell holds two electrons, the second shell up to eight.
Shells close to the nucleus must be filled first.

Isotopes

Isotopes are different atoms of the same element.
They have the same number of protons and electrons but different numbers of neutrons.
Identical chemical characteristics but different atomic masses
Example: Carbon-12, Carbon-13, Carbon-14 (all have 6 protons and 6 electrons but different numbers of neutrons).
Weighted average of atomic mass for all isotopes gives the average atomic mass for that element.

Radioisotopes

Contain excess neutrons, making them unstable
Lose nuclear components as high-energy radiation
Examples of radiation: alpha particles, beta particles, and gamma rays
Physical half-life: the time it takes for 50% of a radioisotope to become stable.
Biological half-life: the time it takes for half the radioactive material to be eliminated from the body.

Chemical Stability and the Octet Rule

Periodic table organized into periods (horizontal rows) and groups (columns)
Each column has a similar valence electron configuration.
Elements in column VIIIA have a full valence shell and are chemically stable (e.g., Helium, Neon).

Ions and Ionic Compounds

Atoms with a positive or negative charge are called ions
Ions are formed by atoms gaining or losing electrons
Ionic compounds are structures formed from positively and negatively charged ions.
Ions are held together by electrostatic forces in a lattice structure.
Examples of ionic compounds: table salt (NaCl), magnesium chloride.

Covalent Bonds, Molecules, and Molecular Compounds

In covalent bonds, atoms share electrons
Molecules are structures composed of two or more atoms bonded covalently, or a single atom
Molecular formulas indicate the number and type of atoms in a molecule.
Structural formulas show how atoms are arranged in a molecule.
Example molecules: carbon dioxide (CO2), water (H2O)
Types of bonds: single, double, and triple covalent bonds

Isomers

Isomers have the same molecular formula but different structural formulas.
Example: glucose, galactose, fructose (all have the same molecular formula C6H12O6 but different structures)

Nonpolar and Polar Covalent Bonds

Electronegativity is the relative attraction of atoms for electrons.
In a covalent bond, unequal sharing creates a polar bond (partial charges).
Equal sharing creates nonpolar bond (no partial charges).
Example: Water (H2O) is polar with the oxygen atom having a partial negative charge and hydrogens having a partial positive charge.

Amphipathic Molecules

Molecules with both polar and nonpolar regions
Example: phospholipids, which have a polar head and nonpolar tails.

Intermolecular Attractions

Weak forces between molecules
Important for the shape and function of larger molecules like DNA and proteins
Examples: hydrogen bonds, Van der Waals forces
Hydrophobic interactions: repulsion between nonpolar molecules in a polar solvent.
Hydrophilic interactions: attraction between polar molecules or ions and water

Water

Water is a polar molecule with slightly positive hydrogen atoms and slightly negative oxygen atoms.
Polarity allows water to form hydrogen bonds with other molecules.
Water's properties: high specific heat, high heat of vaporization, universal solvent, cohesive and adhesive properties, and surface tension.
Water as a solvent: substances that dissolve readily in water are called hydrophilic ("water-loving"), and those that do not dissolve are hydrophobic ("water-fearing"). Example: water is capable of dissolving ionic compounds such as NaCl, and polar compounds like glucose and alcohol.
The role of water in biological systems: essential role in solubility, transport, lubrication, and cushions.

pH, Neutralization, and the Action of Buffers

pH is a measure of hydrogen ion (H+) concentration in a solution.
Acids release H+ ions into a solution, whereas bases absorb H+ ions.
Neutralization is the process of returning an acidic or basic solution to neutral pH (typically 7).
Buffers are substances that help maintain a stable pH by absorbing or releasing H+ ions.

Water Mixtures

Mixtures are formed from combining two or more substances that are not chemically changed.
Common types of mixtures: suspensions, colloids, and solutions
Colloids and suspensions: larger particles, colloids remain mixed but suspensions may settle or require agitation, example Blood
Solutions: smallest particles, does not scatter light or settle, example water solutions.

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Description

Test your knowledge on fundamental chemistry concepts, including atomic structure, elements, pH, and buffer systems. Questions cover topics such as atomic mass, protons, neutrons, and the properties of acids and bases. Challenge yourself to see how well you understand the building blocks of matter.