Lecture 1: Chapter 1-6: SI Units and Scientific Notation - Key Concepts

Flashcards covering SI units, the need for units, and the basics of scientific notation and operations in scientific notation based on the lecture notes.

What are the SI base units for length, mass, time, current, temperature, and amount of substance?

Length: meter (m); Mass: kilogram (kg); Time: second (s); Current: ampere (A); Temperature: kelvin (K); Amount of substance: mole (mol).

Why is it important to specify units with a measurement?

Because a number without a unit has no meaning; units specify what quantity is being measured and enable correct interpretation and calculations.

What system of units is used in chemistry for standardization?

The International System of Units (SI); it uses units like meter (m), kilogram (kg), second (s), ampere (A), kelvin (K), and mole (mol).

What does scientific notation express?

A number as a mantissa multiplied by a power of 10, written as mantissa × 10^exponent.

In scientific notation, how do you decide where to move the decimal when the exponent is negative or positive?

Negative exponent means move the decimal to the left; positive exponent means move the decimal to the right.

Convert 568.762 to scientific notation.

5.68762 × 10^2.

What must you do before adding or subtracting numbers in scientific notation?

Rewrite both numbers so they have the same exponent.

If you have 1.23 × 10^4 and 4.56 × 10^3, how can you add them in scientific notation?

Rewrite 4.56 × 10^3 as 0.456 × 10^4 and add: 1.23 × 10^4 + 0.456 × 10^4 = 1.686 × 10^4.

How do you multiply numbers in scientific notation?

Multiply the mantissas and add the exponents: (a × 10^m)(b × 10^n) = (a × b) × 10^(m+n).

How do you divide numbers in scientific notation?

Divide the mantissas and subtract the exponents: (a × 10^m)/(b × 10^n) = (a/b) × 10^(m−n).

What is a quick check when adding two numbers with negative exponents?

The result should have a negative exponent (the exponent remains negative).

How are exams sometimes graded with respect to 10^0 notation?

Exams may check answers using scientific notation; even if the value is 1, you may need to present as 1 × 10^0; otherwise it could be marked wrong.