LECT 3- Chemistry of Life

Comprehensive flashcards covering the basic chemistry of life including elements, atomic structure, chemical bonding, and chemical reactions.

What is the definition of matter?

Matter is anything that takes up space and has mass.

How is an element defined?

An element is a substance that cannot be broken down to other substances by chemical reactions.

What is a compound?

A compound is a substance consisting of two or more elements in a fixed ratio, with characteristics different from those of its elements.

Which four elements make up $96\%$ of living matter?

Carbon, hydrogen, oxygen, and nitrogen.

What percentage of the 92 natural elements are considered essential elements required for life?

$$20\text{--}25\%$$

What are trace elements?

Elements required by an organism in only minute quantities, typically making up less than $0.01\%$ of body mass.

What are the three subatomic particles and their respective charges?

Neutrons (no charge), protons (positive charge), and electrons (negative charge).

What determines an element's atomic number?

The number of protons in its nucleus.

How is the mass number of an atom calculated?

It is the sum of protons plus neutrons in the nucleus.

What are isotopes?

Isotopes are two atoms of an element that differ in the number of neutrons.

What occurs during the process of radioactive isotope decay?

The isotopes decay spontaneously, giving off particles and energy.

What is meant by the half-life of an isotope?

The fixed rate at which a "parent" isotope decays into its "daughter" isotope.

How is potential energy defined in the context of matter?

The energy that matter possesses because of its location or structure.

Where are electrons found and how does their location relate to energy?

Electrons are found in electron shells; their potential energy is based on their distance from the nucleus, with shells farther away having higher energy levels.

What determines the chemical behavior of an atom?

The distribution of electrons in the electron shells, mostly determined by the number of valence electrons in the outermost shell.

What is an electron orbital?

A three-dimensional space where an electron is found $90\%$ of the time.

What is a covalent bond?

The sharing of a pair of valence electrons by two atoms.

What is the difference between a single and double covalent bond?

A single bond shares one pair of valence electrons, while a double bond shares two pairs.

What is electronegativity?

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

What characterizes a polar covalent bond?

One atom is more electronegative, resulting in unequal sharing of electrons and creating partial positive or negative charges.

What is an ionic bond?

The transfer of electrons from one atom to another, typically between metals and nonmetals, resulting in oppositely charged ions.

What are cations and anions?

A cation is a positively charged ion; an anion is a negatively charged ion.

How does a hydrogen bond form?

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 are Van der Waals interactions?

Attractions between molecules that are close together as a result of charges accumulating by chance in one part of a molecule (dipole-dipole interaction).

In a chemical reaction, what are reactants and products?

Reactants are the starting molecules, and products are the resulting molecules.

What is the chemical equation for photosynthesis?

$$6\,CO_2 + 6\,H_2O \rightarrow C_6H_{12}O_6 + 6\,O_2$$

When is chemical equilibrium reached?

When the forward and reverse reactions occur at the same rate and the relative concentrations of reactants and products do not change.