CHEM Exam1

Chaptee E,1,2

How do you convert Celsius to Kelvin?

K = °C + 273.15

How do you convert Kelvin to Celsius?

°C = K − 273.15

How do you convert Celsius to Fahrenheit?

°F = (°C × 9/5) + 32

How do you convert Fahrenheit to Celsius?

C = (°F − 32) × 5/9

What is a significant figure?

All certain digits plus one estimated digit

Are leading zeros significant?

No

When are trailing zeros significant?

Only when a decimal is present

Sig fig rule for multiplication/division

: Fewest significant figures

Sig fig rule for addition/subtraction

Fewest decimal places

What is the formula for density?

Density = mass ÷ volume

What units are common for density?

g/mL, g/cm³, kg/L

What is a conversion factor?

A ratio equal to 1 used to convert units

What is dimensional analysis?

A method using conversion factors to change units

What are the three states of matter?

Solid, liquid, gas

What is an element?

A substance made of one type of atomWhat is a compound?

What is a compound?

Two or more elements chemically bonded

What is a mixture?

A physical combination of substances

What is the Law of Definite Proportions?

A compound always has the same mass ratio of elements

What is the Law of Multiple Proportions?

Mass ratios of elements in different compounds form small whole numbers

What is the atomic number (Z)?

Number of protons

What is the mass number (A)?

Protons + neutrons

What is an isotope?

Same element, different number of neutrons

What is the formula for atomic mass?

Σ (fraction × mass)

What is Avogadro’s number?

6.022 × 10²³ particles per mole

What is the mole?

A counting unit equal to 6.022 × 10²³ particles

How do you convert moles to atoms?

Multiply by Avogadro’s number

How do you convert atoms to moles?

Divide by Avogadro’s number

How do you convert mass to moles?

Moles = mass ÷ molar mass

How do you convert moles to mass?

Mass = moles × molar mass

What is the speed of light?

3.00 × 10⁸ m/s

What is the relationship between wavelength and frequency?

c = λν

What happens to frequency when wavelength increases

Frequency decreases

What is the photon energy equation?

E = hν

What is Planck’s constant?

6.626 × 10⁻³⁴ J·s

What is the de Broglie wavelength equation?

λ = h ÷ (mv)

What does quantum number n represent?

Energy level

What does quantum number l represent?

Orbital shape

What does quantum number mₗ represent?

Orbital orientation

What does quantum number mₛ represent?

Electron spin

What are the possible values of l for n = 3?

0, 1, 2

What shape is an s orbital?

Spherical

What shape is a p orbital?

Dumbbell

What is the hydrogen energy level equation?

Eₙ = −2.18 × 10⁻¹⁸ J × (1/n²)

What happens when an electron moves to a lower energy level?

Energy is released (emission)

What happens when an electron moves to a higher energy level?

Energy is absorbed

What is the equation for hydrogen transition energy?

ΔE = −2.18 × 10⁻¹⁸ (1/nf² − 1/ni²)