Lecture Notes: Cell Size Hierarchy, Atomic Structure, and Covalent/Ionic Bonding

A set of Q&A flashcards covering cell size hierarchy, atomic structure, ions, and covalent/ionic bonding concepts from the notes.

Which statement correctly ranks the sizes of the following from largest to smallest: prokaryotic cells, macromolecules, eukaryotic cells, viruses, atoms?

Eukaryotic cells > prokaryotic cells > viruses > macromolecules > atoms.

What is an element?

An element is a substance consisting of a single type of atom.

What is the basic structure of an atom?

Nucleus contains protons and neutrons and holds most of the mass; electrons are located in orbitals outside the nucleus.

What are the charges of the subatomic particles?

Protons have +1 charge, neutrons have 0 charge, electrons have -1 charge.

How is electrical neutrality achieved in an atom?

The number of protons equals the number of electrons.

What is meant by an ion?

An atom or molecule with a net electrical charge (positive or negative).

How can positive and negative ions bond?

A positively charged ion and a negatively charged ion attract electrostatically and bond; the resulting ions typically have full electron shells.

What is ionic bonding?

An electrostatic attraction between oppositely charged ions.

What is covalent bonding?

A type of chemical bond formed when atoms share electrons.

Which element commonly forms four covalent bonds?

Carbon; it can participate in four covalent bonds.

What are the two types of covalent bonds?

Nonpolar covalent bonds and polar covalent bonds.

What determines whether a covalent bond is polar or nonpolar?

The electronegativity difference between the bonding atoms.

What is electronegativity?

A measure of how strongly an atom attracts electrons; EN varies between elements.

What characterizes a nonpolar covalent bond?

Electrons are shared equally because the electronegativities are similar.

What characterizes a polar covalent bond?

Electrons are shared unequally due to different electronegativities.

What threshold values of electronegativity difference distinguish polar from nonpolar covalent bonds?

< 0.5: nonpolar covalent; ≥ 0.5: polar covalent.