Chemistry Chapter 2a - Scientific Notation

What does SI stand for?

The International System of Units

What are SI Units?

measurements/units made by scientists to determine size, length, mass, time, and other physical properties of matter

What is SI?

the standard system of measurement used worldwide by scientists

What are the two types of numbers used in science?

1, Counted/defined numbers 2. Measured numbers

What are counted/defined numbers?

Exact numbers that have no uncertainty

What are measured numbers?

Numbers that have uncertainty and are subject to error

True or false: every measurement has a certain level of uncertainty?

True

What digit in any measurement is considered uncertain/estimated?

The last digit

What are significant figures?

All certain and uncertain digits in measurement

What are significant figure rules?

Rules used to determine the significance of a digit

When should a rounded digit be dropped?

When it is less than 5

When should a rounded digit be increased?

When it is equal to or greater than 5

The number of significant figures in your final answers should…

have the same amount of significant figures as the amount with the least amount of significant figures

The amount of significant figures in an answer after multiplying/dividing should…

equal the same as measurement with least significant figures

Least number of significant figures…

wins.

When adding or subtracting, decimal places in your answer should be…

equal to measurement with fewest decimal places

Any unit can be converted into another using…

conversion factor

What is conversion factor?

A number used to change one unit of measurement to another by multiplying or dividing.

What does conversion factor do?

It shows the relationship between two different units

Conversion factor is also…

written in the form of a fraction which represents any equality in units or ratio of equivalent measurements.

What are the steps of conversion of units?

1. Determine the initial unit given and final unit given

2. Plan the steps to convert initial unit into final unit

3. Set up problem by arranging units that cancel each other in the numerator and denominator

What is dimensional analysis?

A method used to convert units and solve problems by treating units like numbers. It involves multiplying by conversion factors to cancel out the unwanted units and make sure the calculation works out with the correct units at the end.

What is volume?

Volume is the amount of space an object occupies

What are the common units for volume?

cm³ and mL

What is cm³ used to measure?

the volume of an object in solid form

What is mL used to measure?

the volume of an object in liquid form

What is density?

mass per unit volume of a material

What are the common units for density?

g/cm³ (for solids) or g/mL (for liquids)

Density is ____ _____ to the mass of an object

directly proportional

For density, higher mass equals…

higher density

Density is _______ ______ to the volume of an object

inversely/indirectly proportional

As volume gets smaller…

density gets larger

What is the formula for density?

D=m/v

Objects FLOAT in liquids when…

their density is lower than the density of the liquid.

Least dense liquid/object will always be…

on the top