CHEMISTRY

Length (SI Base Quantity)

Meter (m) - Formula: DVT

Mass (SI Base Quantity)

Kilogram (kg) - Formula: MDV

Time (SI Base Quantity)

Second (s) - Formula: DVT

Temperature (SI Base Quantity)

Kelvin (K) - K = °C + 273.15

Amount of substance (SI Base Quantity)

Mole (mol) - Formula: n = m/M

Electric current (SI Base Quantity)

Ampere (A) - Formula: I = Q/t

Luminous intensity (SI Base Quantity)

Candela (cd) - No formula needed.

D for DVT

D = Distance.

V for DVT

V = Velocity.

T for DVT

T = Time.

M for MDV

M = Mass.

D for MDV

D = Density.

V for MDV

V = Volume.

1 kg equals how many grams?

1000 g.

1 g equals how many milligrams?

1000 mg.

1 L equals how many mL?

1000 mL.

1 mL equals how many cm³?

1 cm³.

1 m equals how many centimeters?

100 cm.

1 km equals how many meters?

1000 m.

How to convert Celsius to Kelvin?

Add 273.15.

How to convert Kelvin to Celsius?

Subtract 273.15.

Significant figures definition

Meaningful digits in a measurement.

Significant: Nonzero digits

Always significant.

Significant: Zeros between nonzero

Significant.

Significant: Leading zeros

NOT significant.

Significant: Trailing zeros after decimal

Significant.

Significant: Trailing zeros in whole numbers

Ambiguous.

How many significant figures in 456?

3 significant figures.

How many significant figures in 0.0045?

2 significant figures.

How many significant figures in 500?

Generally 1 significant figure.

Accuracy definition

Closeness to the true or accepted value.

Precision definition

Closeness of measurements to one another.

High accuracy + high precision meaning

Close to true value and close together.

Low accuracy + high precision meaning

Far from true value but close together.

Density formula

Density (D) = Mass (M) / Volume (V).

Common density units

g/cm³ or g/mL.

Effect of temperature increase on volume

Volume increases.

Effect of temperature increase on density

Density generally decreases.

Percent error formula

Percent Error = |Experimental - Accepted| ÷ Accepted × 100.

Systematic error definition

Consistent/repetitive error.

Random error definition

Unpredictable variation between measurements.

Natural error caused by

Environmental conditions.

Instrument error caused by

Imperfect or poorly calibrated equipment.

Human error caused by

Physical limitations or inconsistent actions.

Dalton's contribution to the periodic table

Assigned atomic weights to early elements.

Dobereiner's contribution to the periodic table

Grouped elements into triads based on similar properties.

Newlands' contribution to the periodic table

Noticed repeating properties every eighth element.

Mendeleev's contribution to the periodic table

Arranged elements by atomic mass and chemical properties; left gaps for undiscovered elements.

Moseley's contribution to the periodic table

Arranged elements by atomic number.

Atomic number definition

Number of protons in an atom.

Neutral atom condition

Protons equal electrons.

Isotope definition

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

What are periods in the periodic table?

Horizontal rows.

What are groups in the periodic table?

Vertical columns.

Metals position on the periodic table

Left and center.

Nonmetals position on the periodic table

Upper-right.

Metalloids position on the periodic table

Along the stair-step line.

Electronegativity definition

Ability of an atom to attract electrons in a chemical bond.

Highest electronegativity element

Fluorine (F).

Ionization energy definition

Energy required to remove an electron from a neutral gaseous atom.

Electron affinity definition

Tendency of a neutral atom to gain an electron.

Atomic radius definition

Size/distance from nucleus to outermost electron shell.

Reactivity definition

Ability to undergo a chemical reaction.

What happens to atomic radius down a group?

Increases towards the bottom-left.

Most reactive nonmetal position

Upper-right.

Significant figures and leading zeros

Leading zeros are NOT significant.

Percent-error steps

Subtract, absolute, divide, then multiply by 100.

Systematic errors affect

Accuracy.

Random errors affect

Precision.

How do you reduce random error?

By repeating measurements and averaging.

Dalton's atomic weights year

1808.

Dobereiner's triads year

1817.

Newlands' octaves year

1864.

Mendeleev's periodic table year

1869.

Moseley's atomic number year

1913.

Periodic trend: Electronegativity increases

Toward the upper-right.

Periodic trend: Atomic radius increases

Toward the bottom-left.

Periodic trend: Metal reactivity increases

Toward the bottom-left.

Periodic trend: Nonmetal reactivity increases

Toward the upper-right.

Generalization for periodic trends

Upper-right pulls/wants electrons; bottom-left bigger atoms + more reactive metals.

Exception for electron affinity

Chlorine (Cl) has the highest electron affinity, not Fluorine.

Density change of water from 0°C to 4°C

Density increases as temperature increases.

Why does ice float?

Because it is less dense than liquid water.

Freezing water structure

Open hydrogen-bond structure leading to increased volume and decreased density.