Honors Chemistry – Pearson-Aligned Knowt Study Guide

Flashcards covering major topics in Honors Chemistry, focusing on atomic theory, subatomic particles, atomic structure, the periodic table, and polyatomic ions.

Who proposed that matter is made of indivisible particles called atomos?

Democritus (~400 BCE).

What did John Dalton contribute to atomic theory?

He proposed the first scientific atomic theory: atoms are indivisible, identical by element, and combine in whole-number ratios.

Which part of Dalton’s theory was later proven incorrect?

Atoms are divisible (contain protons, neutrons, electrons) and can differ in isotopes.

Who discovered the electron and how?

J.J. Thomson, using the cathode ray tube experiment.

What did Rutherford discover in the gold foil experiment?

The atom’s nucleus—dense, positive, and tiny compared to total atom size.

What did Bohr’s model introduce?

Electrons orbit in quantized energy levels.

Why was Bohr’s model replaced?

It only worked for hydrogen; modern quantum mechanics uses orbitals, not fixed orbits.

Who formulated the uncertainty principle?

Werner Heisenberg.

What does Schrödinger’s model describe?

Electrons as wave-like particles with probability clouds.

What is the modern atomic model called?

The quantum-mechanical or electron cloud model.

What are the three main subatomic particles?

Protons, neutrons, and electrons.

Where are protons and neutrons located?

In the nucleus.

Where are electrons located?

In the electron cloud around the nucleus.

What are the charges of protons, neutrons, and electrons?

Proton +1, neutron 0, electron –1.

Which particle determines the element’s identity?

Protons (atomic number).

Which particle changes to form ions?

Electrons.

Which particle changes to form isotopes?

Neutrons.

What are the relative masses of protons, neutrons, and electrons?

Protons ≈ neutrons ≈ 1 amu; electrons ≈ 1/1836 amu.

Define atomic number.

Number of protons in the nucleus.

Define mass number.

Sum of protons and neutrons.

How do you calculate number of neutrons?

Neutrons = Mass Number – Atomic Number.

How does an atom become a cation?

Loses electrons → positive charge.

How does an atom become an anion?

Gains electrons → negative charge.

What information is needed to construct a nuclear symbol?

Element symbol, atomic number, mass number, and charge (if any).

What is the format for nuclear symbols?

A on top, Z below, and element symbol (example: 23/11 Na■).

What are metals, nonmetals, and metalloids?

Metals: left/center, conduct heat/electricity; Nonmetals: upper right, poor conductors; Metalloids: border staircase, have mixed properties.

What do elements in the same group share?

Same number of valence electrons → similar chemical behavior.

What are Groups 1, 2, 17, and 18 called?

Alkali metals, alkaline earth metals, halogens, and noble gases.

What are transition metals?

Groups 3–12, variable oxidation states, often form colored compounds.

What is the common charge for Alkali metals (Group 1)?

+1.

What is the common charge for Alkaline earth metals (Group 2)?

+2.

What is the common charge for Boron group (Group 13)?

+3 (e.g., Al³■).

What is the common charge for Nitrogen group (Group 15)?

–3.

What is the common charge for Oxygen group (Group 16)?

–2.

What is the common charge for Halogens (Group 17)?

–1.

What is the common charge for Noble gases (Group 18)?

0 (generally inert).

What are exceptions for transition metal charges?

Zn always forms Zn²■; Ag always forms Ag■; Cd forms Cd²■; Al forms Al³■.

Why is average atomic mass rarely a whole number?

Because it’s an average of multiple isotopes.

Define average atomic mass.

The weighted average of all naturally occurring isotopes of an element.

How do you calculate average atomic mass?

Multiply each isotope’s mass by its fractional abundance and add them.

Define percent abundance.

The percentage of each isotope found in nature.

What is the formula for Acetate?

C2H3O2 +1

What is the formula for Bicarbonate?

HCO3 -1

What is the formula for Nitrite?

NO2 -1

What is the formula for Nitrate?

NO3 -1

What is the formula for Cyanide?

CN -1

What is the formula for Hydroxide?

OH  -1

What is the formula for Permanganate?

MnO4 -1

What is the formula for Hypochlorite?

ClO -1

What is the formula for Chlorite?

ClO2 -1

What is the formula for Chlorate?

ClO3 -1

What is the formula for Perchlorate?

ClO4 -1

What is the formula for Sulfite?

SO3 -2

What is the formula for Sulfate?

SO4 -2

What is the formula for Carbonate?

CO3 -2

What is the formula for Oxalate?

C2O4 -2

What is the formula for Chromate?

CrO4 -2

What is the formula for Dichromate?

Cr2O7 -2

What is the formula for Phosphite?

PO3 -3

What is the formula for Phosphate?

PO4 -3

What is the formula for Ammonium?

NH4 -1