Regents Chemisrty

What is the speed of electromagnetic radiation in a vacuum?

$$c = 3.00 \times 10^8 \, \text{m/s}$$

How are wavelength ($\lambda$) and frequency ($\nu$) related?

They are inversely proportional: $c = \lambda \nu$.

What is the formula for photon energy?

$E = h\nu = \frac{hc}{\lambda}$.

What is the classification of visible light from longest to shortest wavelength?

Red > Blue > Violet.

What type of radiation falls above violet light in the electromagnetic spectrum?

Ultraviolet (UV) radiation.

What is the significance of electron transitions in bright-line spectra?

Absorption leads to an excited state and emission leads to a characteristic photon release.

What is a Lewis Electron-Dot Diagram?

A diagram representing the valence electrons of an atom as dots around its chemical symbol.

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

Proton: charge +1, mass 1 amu; Neutron: charge 0, mass 1 amu; Electron: charge -1, negligible mass.

Define electrical neutrality in an atom.

When the number of protons equals the number of electrons.

What are isotopes?

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

What is the nuclear charge of Silicon ($^{28}_{14}\text{Si}$) ?

The nuclear charge is +14.

How is average atomic mass calculated?

$\text{Average Atomic Mass} = \sum (\text{Isotope Mass} \times \text{Fractional Abundance})$.

What is the percent error formula?

$\text{Percent Error} = \frac{\|\text{Measured Value} - \text{Accepted Value}\|}{\text{Accepted Value}} \times 100\%$.

What property defines density?

$D = \frac{m}{V}$ (mass per unit volume).

What determines if an object will float in a fluid?

If its density is less than the fluid's density ($D_{\text{object}} < D_{\text{fluid}}$).

What are intensive properties?

Properties that do not depend on the amount of the substance (e.g., density, boiling point).

What are extensive properties?

Properties that do depend on the amount of substance (e.g., mass, volume).

Describe a physical change.

A change that alters form or state without changing the chemical identity.

What does the law of conservation of mass state?

In a closed system, mass is neither created nor destroyed.

What is the difference between observation and inference?

Observation is factual evidence; inference is a logical interpretation based on observations.