E- Essentials: Sig Figs, Scientific Notation, Dimensional Analysis, Measurements, Density

Flashcards covering core concepts from Sig Figs, scientific notation, dimensional analysis, measurements, and density as presented in the lecture notes.

What is Science?

A framework for gaining and organizing knowledge; a plan of action for processing and understanding information; scientists continually question current beliefs and test ideas through experiments.

What are the main components of the Scientific Method?

Observations, hypothesis, experiments, and conclusions; procedures should be repeatable and controlled; data collected through measurements and analysis.

What is a qualitative observation?

An observation described without numbers or measurements.

What is a quantitative observation?

An observation expressed with numeric measurements.

What is a hypothesis?

A supposition based on available data and observations; a tentative explanation used to design experiments, often in an If… then… form.

What is a control group?

Element in an experiment not manipulated, used as a baseline.

What is an experimental group?

Element in an experiment that is manipulated or tested.

What is a placebo?

A control used in drug testing that resembles the treatment but contains no active ingredient.

What is the placebo effect?

A perceived or actual improvement due to the belief that one is receiving treatment.

What is peer review?

Evaluation by other scientists of results and methods before publication to ensure credibility.

What is density?

Density = mass/volume; a measure of how much matter is packed in a given volume.

What is the SI base unit for length?

Meter (m).

What is the SI base unit for mass?

Kilogram (kg).

What is the SI base unit for time?

Second (s).

What is the SI base unit for temperature?

Kelvin (K).

What is the SI base unit for amount of substance?

Mole (mol).

What is the SI base unit for electric current?

Ampere (A).

What is the SI base unit for luminous intensity?

Candela (cd).

What is dimensional analysis?

A method of converting units using conversion factors so that unwanted units cancel and the desired units remain.

What is an exact number?

A quantity with no uncertainty, obtained by counting or by definition; it has an infinite number of significant figures.

What is a measured number?

A value obtained by measurement, with limited significant figures and associated uncertainty.

What is accuracy?

How close a measurement is to the true value (the bull's-eye).

What is precision?

How reproducible or consistent a set of measurements is across trials.

What is systematic error?

Error that biases results in a consistent direction, reducing accuracy.

What is random error?

Unpredictable fluctuations that affect precision.

What are significant figures?

The total number of meaningful digits in a measurement; includes the last estimated digit.

Trailing zeros: when are they significant?

Trailing zeros are significant only if a decimal point is present in the number (e.g., 50.0 has three sig figs); without a decimal, trailing zeros are not necessarily significant.

What is the rule for significant figures in multiplication and division?

The result contains as many sig figs as the measurement with the fewest sig figs.

What is the rule for significant figures in addition and subtraction?

The result has the same number of decimal places as the measurement with the fewest decimal places.

What is scientific notation?

A way to express numbers as X.XX × 10^n with 1 ≤ X < 10; all digits are significant.

How do you enter numbers in scientific notation on a calculator?

Use the EE button to enter times ten to the power (e.g., 1.2E3).

What is the difference between scientific notation and engineering notation?

Scientific notation uses powers of 10; engineering notation uses powers of 10 in multiples of 3; chemistry typically uses scientific notation.

What is a derived unit?

A unit formed by combining base units (e.g., speed m/s, volume m^3, density kg/m^3).

What is the formula for density?

Density = mass ÷ volume (d = m/v).

What are SI prefixes?

Multipliers that denote powers of 10 (e.g., kilo 10^3, milli 10^-3, micro 10^-6; prefixes range from exa to atto).

What is the volume formula?

Volume = length × width × height (for a rectangular prism).

What are the three major temperature scales and their key points for water?

Fahrenheit: water freezes at 32°F and boils at 212°F; Celsius: freezes at 0°C and boils at 100°C; Kelvin: 0 K is absolute zero; water boils at 373 K and freezes at 273 K.

What is the Kelvin-Celsius conversion formula?

K = C + 273.15; C = K − 273.15.

What is the purpose of averaging measurements and sig figs in reporting?

To reflect measurement uncertainty and maintain accuracy; the last reported digit is an estimate.

What is the difference between measured numbers and exact numbers?

Measured numbers have uncertainty; exact numbers are defined or counted and have infinite sig figs (e.g., 12 inches = 1 foot).