Atoms and Molecules - Practice Flashcards

A set of practice flashcards covering key concepts about atoms, isotopes, bonding, electron structure, and basic biochemical principles from the notes.

What is a chemical compound?

A substance consisting of two or more elements in a fixed ratio with properties different from its constituent elements (e.g., NaCl).

How do covalent bonds differ from ionic bonds?

Covalent bonds share valence electrons between atoms; ionic bonds involve transfer of electrons creating ions that attract.

What is electronegativity?

An atom’s attraction for the electrons in a covalent bond; higher electronegativity means a stronger pull on shared electrons.

What distinguishes nonpolar covalent bonds from polar covalent bonds?

Nonpolar covalent bonds share electrons equally between atoms of similar electronegativity; polar covalent bonds share electrons unequally due to different electronegativities.

What are hydrogen bonds and Van der Waals interactions?

Hydrogen bonds form when a hydrogen covalently bonded to an electronegative atom is attracted to another electronegative atom; Van der Waals are weak, transient attractions between close molecules.

What is an atom's atomic number?

The number of protons in the nucleus; in a neutral atom, it equals the number of electrons.

What is the mass number of an atom?

The sum of protons and neutrons in the nucleus.

What are isotopes?

Atoms of the same element that differ in their number of neutrons; can be stable or radioactive.

What is the half-life of carbon-14 (14C)?

Approximately 5,730 years.

How many protons does carbon have?

6 protons.

How many electrons can the first electron shell hold, and how many can each subsequent shell hold?

First shell holds up to 2 electrons; each subsequent shell holds up to 8 electrons.

What are valence electrons?

The outermost electrons in the valence shell; determine an atom's chemical behavior; full valence shells make an atom inert.

Which subatomic particle is directly involved in chemical reactions?

Electrons.

What happens when electrons absorb or lose energy in relation to their shells?

Electrons absorb energy to move to a higher shell and lose energy to move to a lower shell; energy can be released as heat.

Why does molecular shape matter in biology?

Molecular shape influences how biological molecules recognize and interact with each other, affecting function (e.g., receptor binding).

What are reactants and products in a chemical reaction?

Reactants are the starting molecules; products are the molecules formed after the reaction.

What is the smallest unit of matter that retains the properties of an element?

An atom.

What are the charges of the subatomic particles (protons, neutrons, electrons)?

Protons are positive, neutrons are neutral, electrons are negative.

What element is the most abundant by mass in the human body?

Oxygen (O).

Which four elements make up the majority of body mass (in order)?

Oxygen, Carbon, Hydrogen, and Nitrogen.

Which element most resembles boron chemically (from the periodic table)?

Aluminum (Al).