Chem Review Flashcards
(39 cards)
A Trace Element
required only in minute amounts by living organisms
Elements cannot?
be broken down to other substances by chemical reactions
What is mass number?
the amount of protons + nuetrons
What is atomic number?
number of protons
What are electron shells?
The energy level of electrons at a characteristic average distance from the nucleus of an atom
What is a valence shell?
Where electrons are found in an atom during a chemical reation
whats van der Waals interaction
ability of atoms and molecules to stick together due to ever-changing regions of positive and negative charges
covalent bonds are…
sharing of electrons
How many covalent bonds can oxygen make
2
How do you know how many covalent bonds an atom can make?
By knowing how far away they are from a noble gas
What charge is Hydrogen
positive
What is cohesion
Hydrogen bonds can hold the atoms of a substance together
What is heat?
A measure of matter’s total kinetic energy due to motion of its molecules
What is a Calorie
the amount of heat required to raise the temperature of 1 g of water by 1 degree C
What is Evaporative Cooling
the “hottest” molecules, or the ones with the most kinetic energy, are leaving the surface as a gas.
What is heat of vaporization
The amount of heat 1 gram of a liquid must absorb to become a gas is known as
What does a solvent do
it dissolves things
What does a solute do
it gets dissolved
Whats a hydration shell
When a substance such as salt is dissolved in water, the ions will separate and become surrounded by water molecules
Whats a colliod
when substances that are too large to dissolve in water will remain suspended in the water
Whats the name of OH-
hydroxide ion
Whats the nanme of H3O+
hydronium ion
Whats a buffer?
A substance that minimizes changes in the concentration of hydrogen ions and hydroxide ions in a solution
What determines the cohesiveness of water moloecules?
hydrogen bonds
