Chapter 2 Notes: Mixtures, Atomic Structure, Isotopes, and Mass Spectrometry

A set of practice questions covering mixtures, basic atomic structure, isotopes, ions, and mass spectrometry based on Pages 1–2 of the notes.

What is a heterogeneous mixture?

A mixture that is not the same throughout.

What is a homogeneous mixture (solution)?

A mixture that is the same throughout.

What are physical properties?

Characteristics that can be measured or observed without changing the substance’s composition (e.g., density, conductivity, melting point, color, hardness).

What are chemical properties?

Describe how a substance may change or react to form other substances (e.g., flammability, corrosivity, reactivity).

When do chemical reactions occur?

During chemical changes.

Which particle is the lightest in matter?

Electron.

What does the statement 1 C/s = 1 A mean?

A coulomb of electric charge flowing in one second equals one ampere of current.

How are elements arranged in the periodic table?

In order of increasing number of protons (atomic number).

Why do hydrogen and helium differ in neutrons, according to the notes?

Hydrogen has 1 proton and typically 0 neutrons; helium has 2 protons and 2 neutrons.

What is an isotope?

Atoms with the same number of protons but different numbers of neutrons.

What is the Mass Number A?

A = number of protons + number of neutrons (A = p+ + n0).

What is the Atomic Number Z?

Z = number of protons.

In a neutral atom, how many electrons are present relative to protons?

The same number as protons (electrons = protons).

For the isotope 48Ti, what are P, N, and E?

Protons = 22, Neutrons = 26, Electrons = 22.

What are ions?

Atoms that have gained or lost electrons and thus carry a charge.

What is a cation?

A positively charged ion, usually formed by metals (e.g., Mg2+).

What is an anion?

A negatively charged ion, usually formed by non-metals (e.g., O2−).

For the ion 51V4+, what are P, N, and E (electrons)?

Protons = 23, Neutrons = 28, Electrons = 19.

What is mass spectrometry?

A technique where ionized isotopes are separated based on mass-to-charge ratio, allowing analysis of isotopic abundances.

What are isotopes?

Atoms with the same number of protons but different numbers of neutrons.

What is atomic weight (amu)?

A value that is the weighted average of the element’s isotopic masses based on natural abundances.

What does amu stand for and how is atomic weight determined?

amu = atomic mass unit; atomic weight is the weighted average of isotopic masses, weighted by natural abundances.

Why are elements with lower potential energy considered more stable?

Because lower potential energy corresponds to greater stability (lower energy state).