General Chemistry and Properties of Water

Flashcards reviewing basic atomic structure, chemical bonds, chemical reactions, water properties, and molecular mass calculations based on lecture notes.

What is potential energy as defined in the lecture notes?

Potential energy is the capacity to cause change that matter possesses because of its position.

How does an electron's distance from the nucleus affect its potential energy?

Electrons farther from the nucleus have more energy.

What are the electron capacities for the first, second, and third electron shells?

The first shell holds 2 electrons, the second shell holds 8 electrons, and the third shell holds 18 electrons.

What is an electron orbital?

An orbital is the area around a nucleus where an electron is most likely to be located.

What determines the chemical behavior of an atom?

The chemical behavior of an atom depends on the number of electrons in its outermost shell (valence electrons).

What is the Octet Rule?

The rule stating that atoms interact to establish completely full outer energy levels.

How are oxidation and reduction defined in redox reactions?

Oxidation (OIL) is the loss of electrons, and reduction (RIG/RSG) is the gain of electrons.

How many naturally occurring elements exist and how many are found in living organisms?

There are 90 (or 92) naturally occurring elements, 12 of which are found in living organisms.

What is a chemical compound?

A substance consisting of two or more elements combined in a fixed ratio.

How is an ionic bond formed?

An ionic bond is formed by the attraction of oppositely charged ions.

How is a covalent bond formed?

A covalent bond forms when atoms share two or more valence electrons.

What three characteristics make molecules like $\text{H}_2$ stable?

They have no net charge, the octet rule is satisfied, and there are no unpaired electrons.

What is the difference between single, double, and triple bonds according to the transcript?

A single bond is the sharing of 1 pair of valence electrons, a double bond is the sharing of 2 pairs, and a triple bond is the sharing of 8 pairs.

What is electronegativity?

An atom's attraction for the electrons in a covalent bond.

What distinguishes a polar covalent bond from a nonpolar covalent bond?

In a nonpolar covalent bond, atoms share electrons equally. In a polar covalent bond, atoms do not share electrons equally because one atom is more electronegative, resulting in partial positive or negative charges.

What factors influence the extent of chemical reactions?

Temperature, concentration of reactants and products, and catalysts.

Why is a water molecule polar?

Oxygen is more electronegative than hydrogen, causing the shared electrons in polar covalent bonds to spend more time near the oxygen atom (giving oxygen a partial negative charge and hydrogen a partial positive charge).

What is a hydrogen bond?

A bond that forms when a hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom (usually oxygen or nitrogen in living cells).

What is the difference between cohesion and adhesion in water?

Cohesion is water molecules sticking to together, whereas adhesion is water molecules sticking to other polar substances.

What is surface tension and why is it important for plants?

Surface tension is a measure of how difficult it is to break the surface of a liquid; it is important for the transport of water and dissolved nutrients against gravity.

What is high specific heat and why is it biologically important?

High specific heat means a large amount of energy is required to change water's temperature (measured in $\text{cal}/(\text{g} \times {}^\bullet\text{C})$), which helps maintain homeostasis.

Why does evaporation of water cause cooling?

Water has a high heat of vaporization, so evaporation of water from a surface removes heat and causes cooling.

Why is ice less dense than liquid water at $0^\circ\text{C}$?

At $0^\circ\text{C}$, water molecules are locked into a crystalline lattice where hydrogen bonds keep the molecules far enough apart to make ice less dense.

What is the difference between a hydrophilic and a hydrophobic substance?

A hydrophilic substance interacts with and dissolves in water (polar molecules and ions), whereas a hydrophobic substance does not react well with water (nonpolar).

How are solution, solvent, and solute defined?

A solution is a completely homogeneous liquid mixture, a solvent is the dissolving agent (such as water), and a solute is the substance that dissolves (such as salt).

What is an aqueous solution?

A solution in which water is the solvent.

What is Avogadro's number?

$6.02 \times 10^{23}$ daltons (or molecules per mole).

How is the molecular mass of sucrose ($\text{C}_{12}\text{H}_{22}\text{O}_{11}$) calculated?

Carbon: $12 \times 12 = 144$, Oxygen: $11 \times 16 = 176$, Hydrogen: $22 \times 1 = 22$. Total sum = $144 + 176 + 22 = 342\,\text{daltons}$ ($342\,\text{g/mol}$).