Chapter 2- Matter Flashcards
What is matter?
Anything that has mass and occupies space.
What are 2 types pure substances?
Elements
Compounds
What are the two classifications of matter?
Pure substances
Mixtures
What are the two types of mixtures?
Heterogenous
Homogenous (solutions)
What is an element?
A pure substance which cannot be broken down into anything simpler via physical or chemical means
What is a compound?
A pure substance that can be decomposed by a chemical change into simpler substance with a fixed mass ratio
What is an example of heterogenous mixtures?
Salt and Pepper
What is an example of homogenous mixtures?
Kool-Aid
Even with its vast diversity, all life is based upon ________.
A limited number of chemical elements
What elements comprise the human body?
Oxygen (O) - 65% Carbon (C) - 18.5% Hydrogen (H) - 9.5% Nitrogen (N) - 3.3% Calcium (Ca) - 1.5% Phosphorous (P) - 1.0% Potassium (K) - 0.4% Sulfur (S) - 0.3% Sodium (Na) - 0.2% Chlorine (Cl) - 0.2% Magnesium (Mg) - 0.1% Trace Elements - <0.01%
Every element is composed of _______.
Atoms
Atoms of a given element are ______.
Identical
Atoms of an element are _________ into atoms of another element by chemical processes.
Not changed
Where are protons and neutrons locates?
In the nucleus of an atom
Where are electrons located?
Orbiting in energy levels around the nucleus of an atom
A proton has a _________ charge.
Positive
An electron has a _________ charge.
Negative
A neutron has _________ charge.
No
What is the unit of measure for an atom?
amu
Atomic Mass Unit
1 amu = _______.
The mass of one proton
How much smaller are electrons than 1 amu?
Almost 2,000 times smaller.
Do any elements have the same number of protons?
No
Atomic number =
Number of protons =
What is the mass number?
Protons + Neutrons
Isotopes are comprised of what?
Same # protons, different # neutrons
What is the atomic mass or weight?
The average mass of the atoms of an element
What is the atomic mass of Carbon (C)?
12.011 amu
What can radioactive isotopes be used for?
Diagnostic medicine
Radioactive compounds in metabolic processes act as what?
Tracers
How can radioactive isotopes be traced in living organisms?
Through instruments designed to detect the radioactive isotopes
Are radioactive isotopes harmful to us?
Yes
Uncontrolled radioactive isotope exposure can lead to what?
Damage to some molecules in a living cell (cellular molecules) especially DNA
Chemical bonds are broken by radioactive isotopes causing what?
Abnormal bonds
How are elements arranged on the Periodic Table of Elements?
Left to right, top to bottom in order of increasing atomic number
In the table of elements, what is a row called?
A period
In the table of elements, what is a column called?
A group
What determines an atom’s chemical properties?
The distribution of electrons around the nucleus
Where exactly are electrons located?
In the electron shield
How many electrons can the 1st electron shell hold?
2
How many electrons can the second shell hold?
8
How many electrons can the 3rd shell hold?
18
When is an electron shell considered full?
When it contains 8 electrons
What is the formula for determine the electron amount per shell?
2(n)^2
N=shell number
How many electron shells may an atom have?
1-7 electron shells
What is the outermost electron shell called?
The Valence shell
What determines the chemical properties of an atom?
The number of electrons in the outermost (valence) shell
What may occur to atoms who’s valence shell is not full?
They interact with other atoms in ways that enable them to complete or fill their valence shell
What is the OCTET rule?
Atoms tend to gain, lose, or share electrons so as to have 8 electrons
What are compounds?
Two or more elements chemically combined to form a new substance with new properties
Is sugar a compound or element?
Compound
What is one of the simpler substances sugar can be broken down into?
Carbon (the black element created).
Can Carbon be broken down into a simpler element? Why?
No. Carbon is an element and cannot be further decomposed by chemical or physical means.
What is a radioactive isotope?
One in which the nucleus decays spontaneously, giving off particles and energy.
When a neutral atom loses an electron (-), it becomes a __________ with what kind of charge?
Cation (+)
When a neutral atom gains an electron (-), it becomes a __________ with what kind of charge?
Anion (-)
What are covalent bonds?
When atoms share more than 2 valence electrons.
How many electrons are share in a double covalent bond?
4 electrons are shared
How many electrons are shared in a triple covalent bond?
6 electrons are shared.
How many electrons are shared in a covalent bond?
2 electrons are shared.
Chemical reactions do what to chemical bonds?
Make or break chemical bonds
What is a reactant?
The compounds exposed to a chemical reaction
What is the end result of a chemical reaction called?
Product(s)
Matter neither is created nor destroyed, so what occurs to
(2)H2 + O2 when it reacts?
(2)H20
What are molecules?
Combinations of atoms held together by covalent bonds to form compounds
(H20)
What is electronegativity?
The atom’s affinity for electrons
What dictates how electrons are distributed in a covalent bond?
Differences in electronegativity
What are nonpolar covalent bonds?
Equal sharing of electrons
What are polar covalent bonds?
Unequal sharing of electrons
Why is H20 a polar covalent bond?
Because the atoms are not sharing electrons evenly
Why is one side of water negatively charged?
Because the oxygen atom keeps the electrons longer than the hydrogen atoms, creating a negative charge.
The oxygen side of water charged how?
Positively charged
What are the 7 properties of water?
- Adhesion
- Cohesion
- Capillary action
- High surface tension
- Holds heat to regulate temperature (high heat capacity
- Less dense as a solid than a liquid
- Universal solvent
Water is Adhesive to what type of molecules?
Any substance it can form hydrogen bonds with
What does adhesion refer to?
Attraction to other polar substances
What property is related to cohesion?
Surface tension
What does cohesion refer to?
It refers to attraction to other water molecules (like molecules)
What is surface tension?
The measure of the force necessary to stretch or break the surface of a liquid.
Surface tensions makes water behaves as if….
It were covered by an invisible film
Due to surface tension, what can some animals do on water?
Stand, walk, or run without breaking the surface
When is capillary action present?
When a molecules has both adhesive and cohesive attributes
What is capillary action? (H20)
Water is attracted to another material (adhesion) and through COHESION other water molecules move too as a result of the original cohesion
Flubber is an example of ….
Capillary action 😂
Water has a high specific heat. What does that mean?
A very high temperature is required to changes the molecules’ temperature (H2O)
Water has a high heat of vaporization. What is a result of vaporization?
The evaporation of water from a surface causes cooling of that surface (evaporative cooling)
Each water molecule can form up to ______ with neighboring water molecules
4 H-bonds
What occurs to H bonds of water in a liquid state?
They are constantly formed and broken
Why does water have a high melting/boiling point?
Because it requires a lot of thermal energy (heat) to break the H bonds of water
Why is water less dense as a solid than a liquid?
Because the molecules are spread further than a liquid
Hydrogen bonds in ice are stable/unstable?
Stable
The Hydrogen Bonds in liquid water are stable/unstable?
Unstable
Why is water a solvent?
It dissolves salts by forming a shell of interacting water molecules around the ions. This weakens the electrostatic interactions between the ions
Because unlike charges attract, the negative end of water (H2O) will be attracted to ________ .
The positive end of salt, Na(+).
Because unlike charges attract, the positive end of water (H2O) will be attracted to ________ .
The negative end of Salt: the negative chloride ion, Cl (-)
Once water attaches to salt, what occurs?
Due to the fluid nature of water, it pulls upon the ionic compound of salt (Na- Cl+) until their ionic bond is broken and the ionic molecules move away from from each other (dissolving)
What is a solution?
A mixture of two or more substances in a single phase
What are the two TYPES of substances in a mixture?
1 solvent
2+ solutes
What types of molecules can form H-bonds with water?
Polar molecules with electronegative atoms
What are hydrophilic compounds?
Compounds that easily dissolve in water
Hydrophilic comes from the Greek “?”
“Water-loving”
What are hydrophobic compounds?
Compounds that do no readily dissolve in water
Hydrophobic means “?”
“Water-hating”
Why does oil and water not mix?
Oil is non polar
Water is polar
Only polar compounds can form bonds with H20
Because water is an cohesive molecule, explain why oil and water do not mix.
Water is attracted to itself through its polar negativity (cohesion). Oil has no polar negativity. Water will attempt to join like molecules, push the non-polar molecules out of the way in.
In LIQUID water, a small percentage of water molecules break apart into what?
Ions
What ions are produced in liquid water?
Hydrogen ions (H+) Hydroxide ions (OH-)
Ionizing a water molecule (H2O) results in what?
(H+) + (OH-)
Hydrogen ion + hydroxide ion
Hydrogen and hydroxide ions are very __________.
Reactive
What is an acid?
A substance that produces H+ ions when dissolved in water (hydrogen ions increase)
What is a base?
A substance that produces OH- ions when dissolved in water
What is the pH scale?
A scale describing how acidic or basic a solution is
What is the range of the pH scale?
Most Acidic (0)
to
Most Basic (14)
What does each unit of the pH scale represent?
Each pH units represents a 10-fold change in the H+ concentration in a solution
Name a few examples of base, neutral, and acidic solutions.
Base- (.5) battery acid, lemon juice, gastric juice
Neutral- human urine, saliva, pure water, human blood, tears, seawater
Acid- (13) oven cleaner, (11) household bleach, household ammonia
What is a buffer?
A substance that minimizes changes in pH
What do buffers do chemically?
- Accept H+ ions when in excess
- Donate H+ ions when depleted
The chemistry of life is sensitive to what?
Acidic and basic conditions
What are isotopes?
One of several forms of an element, each with the same number of protons, but different number of neutrons.
What are groups specifically?
Elements in a vertical column have the same number of electrons in their valence shell
What do elements of a group share?
Chemical properties
What is a period of The Periodic Table, specifically.
Each horizontal row contains elements with the same total number of electron shells.
Across each period, elements are ordered in increasing atomic number.
How does evaporative cooling occur?
Molecules with the greatest energy leave (evaporate) thus lowering the temperature of remaining molecules allowing for heat to leave while the surface remains cool.
