Atomic Theory

What is matter?

Matter is any substance that has mass and occupies space.

What are the fundamental building blocks of matter?

Atoms are the basic units of matter.

What are the three states of matter?

The three states of matter are gases, solids, and liquids.

How does Dalton's Atomic Theory define matter?

Matter consists of atoms, which are the smallest identifiable unit of matter and cannot be destroyed.

What does the Law of Conservation of Mass state?

Mass can neither be created nor destroyed in a chemical reaction; it is conserved.

What is the Law of Definite Proportions?

In a chemical compound, the mass ratio of elements stays the same no matter where it comes from.

What is the difference between a cation and an anion?

Cations are positive ions from losing electrons; anions are negative ions from gaining electrons.

What is an isotope?

Isotopes are atoms of the same element that differ in their number of neutrons.

What is Avogadro’s Number?

Avogadro’s Number is defined as the number of atoms in exactly 12 g of carbon-12, which is 6.022 × 10^23 individual units.

How do you convert from moles to atoms?

To convert from moles to atoms, multiply by Avogadro’s number.

What is molar mass?

Molar mass is the mass of exactly 1 mole of an element expressed in g/mol.

How is the molar mass of a compound calculated?

The molar mass of a compound is the sum of the atomic masses of each atom in the compound.

What did J.J. Thomson contribute to atomic theory?

J.J. Thomson discovered the electron and proposed the Plum-Pudding Model of the atom.

What was the outcome of Rutherford’s Gold Foil Experiment?

Rutherford concluded that every atom has a positively charged dense center called the nucleus.

What determines an atom's atomic number?

An atom's atomic number is determined by the number of protons within its nucleus.

What does the Law of Multiple Proportions state?

When an element forms a series of compounds, the ratio of the masses of one element to a fixed amount of the second element is a ratio of small whole numbers.

How do you calculate an element's atomic mass?

An element's atomic mass is a weighted average of all the masses of its naturally occurring isotopes.

What is the purpose of the mass spectrometry technique?

Mass spectrometry sorts ions by their mass-to-charge ratios (m/z ratios).

What is a homogeneous mixture?

A homogeneous mixture is uniform and consists of one phase.

What is the difference between elements and compounds?

Elements are basic substances that cannot be divided, while compounds are made of two or more elements that can be broken down.

How can one determine the number of molecules in a sample using grams?

Convert grams to moles using molar mass, then multiply by Avogadro’s number to find the number of molecules.