Periodic elements

Atom: smallest particle of an element

molecule: smallest particle of a compound, made up of 2+ atoms

element: pure substance with only 1 type of atom

compound: pure substances made up of 2+ types of atoms

atomic number is how many protons

mass number is protons plus neutrons

what is “relative” scale

relative atomic mass scale - used to describe tiny atoms (convenient)

reference point - 1 atom of ¹²C = 12.0 u (u = unified atomic mass unit)

conversion factor - 1.6605 × 10^-27kg = 1.0 u

finding atoms in 8.2 grams of ⁶Li

1 atom of ⁶Li = 6u

1u = 1.6605 × 10^-24

8.2g / 1.6605 × 10^-24 / 6 = 8.2 × 10²³ atoms

there is never space between electron clouds, they will always be touching

when nonmetal and a metal are bonded it is not a molecule

When converting units that are cubed (like volume) or squared (like area), you need to apply the conversion factor for the base unit the corresponding number of times. Let's break it down:

Area (Squared Units)

If you have a conversion factor for length, say from meters (m) to centimeters (cm), you know that $1 \text{ m} = 100 \text{ cm}$. If you want to convert an area from square meters ($\text{m}^2$) to square centimeters ($\text{cm}^2$), you need to square the conversion factor:

$1 \text{ m}^2 = (100 \text{ cm})^2 = 100^2 \text{ cm}^2 = 10,000 \text{ cm}^2$

So, if you have $5 \text{ m}^2$, you would convert it by multiplying by the squared conversion factor:

$5 \text{ m}^2 \times \left(\frac{100 \text{ cm}}{1 \text{ m}}\right)^2 = 5 \text{ m}^2 \times \frac{10,000 \text{ cm}^2}{1 \text{ m}^2} = 50,000 \text{ cm}^2$

Volume (Cubed Units)

Similarly, for volume, if your base length conversion is $1 \text{ m} = 100 \text{ cm}$, then to convert from cubic meters ($\text{m}^3$) to cubic centimeters ($\text{cm}^3$), you cube the conversion factor:

$1 \text{ m}^3 = (100 \text{ cm})^3 = 100^3 \text{ cm}^3 = 1,000,000 \text{ cm}^3$

For example, to convert $2 \text{ m}^3$ to cubic centimeters:

$2 \text{ m}^3 \times \left(\frac{100 \text{ cm}}{1 \text{ m}}\right)^3 = 2 \text{ m}^3 \times \frac{1,000,000 \text{ cm}^3}{1 \text{ m}^3} = 2,000,000 \text{ cm}^3$

This principle applies to any unit conversion involving squared or cubed dimensions. You raise the conversion factor to the power of the dimension (2 for area, 3 for volume).