Chemistry

Question 1

Compounds

Answer 1

2 or more DIFFERENT elements combined at a FIXED ratio. ALWAYS a molecule.

Question 2

Molecules

Answer 2

2 or more atoms held together by chemical bonds (often covalent). NOT ALWAYS a compound.

Question 3

Atomic number

Answer 3

number of protons. Change number of protons = different element

Question 4

Mass number

Answer 4

Protons + neutrons

Question 5

Atomic Mass

Answer 5

Average of isotopes.

Question 6

We are 96% ______

Answer 6

ONCH. Oxygen, Nitrogen, Carbon and Hydrogen.

Question 7

Atomic Nucleus vs. Nucleus

Answer 7

Atomic Nucleus: Proton + Neutrons.

Nucleus: Chromosomes and the such.

Question 8

Energy Levels

Answer 8

Can go up, but WILL go down.

Question 9

Matter

Answer 9

Anything that has mass and takes up space

Question 10

Element

Answer 10

Substance that cannot be broken down by chemical reaction

Question 11

Required amount of elements

Answer 11

Humans need 25 elements.

Plants need 17 elements.

Question 12

Trace elements

Answer 12

Required in minute amounts

Question 13

Properties of elements

Answer 13

Depend on atomic structure

Question 14

Radioactive Isotopes

Answer 14

An isotope where the nucleus decays spontaneously, giving off particles & energy. (decay into proton, changing the element)

Question 15

Energy

Answer 15

Ability to do work

Question 16

Potential energy

Answer 16

Energy that matter possesses due to its location or environment

Question 17

Energy levels/shells

Answer 17

difference in potential energy of electrons. Ball bouncing down stairs. Cannot stop in-between stairs.

Question 18

Valence Shell

Answer 18

Outermost electron shell. Electron shell are the rings around the nucleus.

Question 19

Electron Orbitals

Answer 19

Area where the electrons have a 90% chance of being found. Fig. 2.8 pg 35

Question 20

Electronegativity

Answer 20

The attraction of an atom for an electron of covalent bonds (lower on left/higher on right side of Periodic Table).

Question 21

Covalent bond

Answer 21

Sharing Electrons. Multiple types, i.e. single or covalent bonds.
Single Bond: H-H
Double Bond: O=O

Question 22

Structural Formula

Answer 22

Shows how atoms and bonds are arranged.

Question 23

Molecular Formula

Answer 23

Also known as chemical formula. Written form, showing atom(s) type and amounts.

Question 24

Valence

Answer 24

Bonding capability of an atom. Usually equals # of electrons required to complete the atom’s outermost valence shell.

Question 25

True Polar Covalent

Answer 25

Nonpolar. H-H

Question 26

Polar Covalent Bond

Answer 26

Outer shell is full at 8 electrons, but electrons are not shared equally. H2O

Question 27

Ionic Bond

Answer 27

Bond between an anion and a cation. Bigger the charge, better the bond.

Question 28

Ion

Answer 28

Charged atom

Question 29

Cation

Answer 29

Positively charged. Loss of an electron

Question 30

Anion

Answer 30

Negatively charged. Gained an electron.

Question 31

Hydrogen Bond

Answer 31

A weak bond between hydrogen & an electronegative atom

Question 32

Van der Walls Interaction

Answer 32

When electrons happen to gather on one side making a very weak polar covalent bond.

Question 33

Bond Strengths

Answer 33

Strongest -> Covalent -> Ionic -> Hydrogen -> Van der Walls interaction -> Weakest.

Question 34

Function in a molecule is related to ?

Answer 34

Size and Shape.

Question 35

Chemical Reactions

Answer 35

Making and breaking bonds

Question 36

Reactants

Answer 36

Starting materials

Question 37

Products

Answer 37

Ending Molecules/Atoms

Question 38

Chemical equilibrium

Answer 38

Reversible, offset one another, no net change. Doesn’t mean concentrations are the same, just a balanced specific ratio. Higher concentration = higher chance of chem. reaction.