Unit 1: Chemistry Flashcards
What are the 9 steps of the scientific method?
- Observe the world around
- Ask questions, privides frame work of experiment
- Research
- Hypothesis
- Experiement
- Collect data
- Analyze data
- Make a conclusion
- Do a follow up experiment
Properties of water
High or low specific heat?
High or low boiling point?
- high specific heat
- high boiling point
- liquid
Matter
Anything that has mass and volume
Element
A pure substance that cannot be broken down any further by ordinary chemical means
Atom
Smallest part of an element that still maintains the chemical and physical properties of that element
Compound
- 2 or more different elements chemically combined to form a new substance
- Can be separated into a simpler subtanvr only by chemical means
- Has properties that are different from the elements they are made from
Atomic number
# of protons Tells us what element it is
How do you find the number of electons?
The number of electrons=number of protons
Atomic mass
The weighted average of all the isotopes for a given element based on their frequency in nature
Valence electrons
Electrons that are found in an atom’s outermost energy level (furthest from the nucleus) these are important because they determine how an atom will bond and react
Group
Also called a family
VERTICAL columns on the periodic table
Elements in the same group have the same number of valence electrons and similar properties
Period
HORIZONTAL rows of the periodic table
Have the same number of energy levels
Covalent bonds
What types of atoms can covalent bonds form?
Formed when 2 atoms share electrons in order to satisfy the octet rule
There are no cations or anions because they are sharing electrons (no charge)
Formed from Nonmetals only
Polar covalent bonds
Atoms are NOT equally sharing electrons because one of the electrons is stronger
Partial charge due to unequal sharing
Nonpolar covalent bonds
Atoms are equally sharing electrons
No charge due to equal sharing
Polarity is the difference in _________ of the atoms bonded together
Electromagnetivity-the ability of an atom to pull electrons towards itself
Electromagnitivity for NPC, PC, and ionic
NPC-less than 0.5
Difference is greater than 1.7-ionic
Difference is greater than 0.5-polar covalent
pH
Power of hydrogen, measure of concentration of H+ ions
measure of acidity
Properties of acids
- sour taste
- changes litmus paper from blue to red
- has the ability to interact with bases to form neutral salts
- pH of 0-6 is acidic
Properties of bases
- another name for base is alkaline
- decreases the hydrogen ion concentration
- can increase the hydroxide ion concentration
- pH of 8-14
- bitter
- slippery
- turns litmus paper from red to blue
- reacts with acids to form saly and water
Why is water a polar molecule?
Because it has an unequal distribution of charges
In a water molecule, what are the oxygen and hydrogen atoms held together by? How do the whole water molecules stick together?
O and H atoms are held together by POLAR COVALENT BONDS
Water molecules are held together by HYDROGEN BONDS
How does a hydrogen bond work?
When a hydrogen atom is part of a Polar covalent bond, its partial + charge allows it to share attractions with other elctronegative atoms. The charged regions on H2O molecules are electrically attracted to oppositely charged regions on neighboring molecules. Since the + charged region in this type of bond is always a hydrogen atom, the bond is a hydrogen bond
How many hydrogen bonds can a H2O molecule have?
up to 4
Cohesion vs. adhesion
Cohesion: the tendency of water molecukles to stick together
Adhesion: the clinging of one substance to another
Surface tension
A measure of how difficult it is to stretch or break the surface of a liquid
How do hydrogen bonds moderate temperature?
Because of hydrogen bonding, water has a better ability to resist temperature changes
Heat must be absorbed in order to break hydrogen bonds, and heat is released when hydrogen bonds form. To raise the temperature of water, heat energy must fisrt disrupt hydrogen bonds before H2O molecules can move faster. So, water absorbs a lot of heat, but only warms up a few degrees.
In what state is water least dense? Why is this important for life on Earth?
Water is least dense as a SOLID, due to hydrogen bonds.
this is important because if ice sank, then eventually, ponds, lakes, and oceans would freeze. Also, the ice insulates the water below from the cold air above, so fish and other aquatic life can survive. 🐢🐋🐳🐬🐙🐟🐠
Why is water a versatile solvent?
Because of the polarity of its molecules
Does an acid give or accept hydrogen (H+) ions to a solution?
Donates
Does a base give or accept andthen remove hydrogen ions from a solution?
A base accepts H+ ions
What does each pH unit on the scale represent?
A tenfold change in the concentration of H+
Why are buffers so important to living organisms?
They contribute to the pH stability in blood and many other interbal solutions.
What is acid precipitation?
Rain snow or fog with a pH lower than 5.6
Why is the formation of H and O to make water a chemical reaction?
Because of the making and breaking of chemical bonds, leading to changes in the composition of matter
Why is carbon so important for life?
How many atoms can carbon bond with?
It is able to form large, diverse molecules.
It can bond to up to 4 other atoms
What is an organic compound
Has carbon based molecules
What is a hydrocarbon?
Are they polar or non polar?
Are they hydrophobic or hydrophilic
An organic compound composed of only carbon and hydrogen
They are nonpolar because of the C–H bond
The are hydrophobic
Hydrophilic vs. hydrophobic
Hydrophilic: water loving
Hydrophobic: water fearing
Capillary action
The ability of a liquid to move through narrow spaces
Carbon skeleton
A chain of carbon atoms in an organic molecule
What is am isomer?
Compounds with the same formula but different structures
