Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
57 Cards in this Set
- Front
- Back
|
What is matter? |
Anything that has mass. |
|
|
States of matter. |
Solid, liquid or gas. |
|
|
What is an element? |
Substance that cannot be broken down into another substance by ordinary chemical means. |
|
|
What is matter composed of? |
Matter nonliving or living is composed of elements. |
|
|
How many elements are there? |
There are 92 elements that are naturally occuring. Each differ from each other in its properties. Property is a physical or chemical characteristic. |
|
|
What are the most important elements? |
Hydrogen (10%), Carbon (18%), Nitrogen (5%), Oxygen (65%), Phosphorus (1.1%) and Sulphur and other elements (0.9%). The earths crust and all organisms are made up of these elements. |
|
|
What is the atomic theory? |
The atomic theory states that elements consist of tiny particles called atoms. |
|
|
Things about atoms: |
Each element consist of only one kind of atoms. It has the same name as its atoms. Atoms are made up of 3 sub particles located in the nucleus: Neutrons, Protons and Electrons. |
|
|
What is a neutron? |
A sub particle which have no electrical charge. |
|
|
What is a proton? |
A sub particle which has a positive electrical charge. |
|
|
What is an electron? |
A sub particle which have a negative electrical charge. |
|
|
What is atomic mass? |
Atomic mass is equal to the sum of the protons and neutrons. |
|
|
What is the atomic number? |
The number of protons in the nucleus of an atom. All atoms have the same number of protons. # of Protons = Atomic number. |
|
|
The periodic table: |
Consist of elements arranged by their characteristics. The elements are grouped vertically and group 8 is the noble gases ( because they rarely interact with another atom). |
|
|
How to find the number of neutrons? |
Subtract the number of protons from the atomic mass and take the closest whole number. |
|
|
What is an isotope? |
Atoms of the same elements that differ in the number of neutrons. |
|
|
Things to know about isotopes: |
They have the same number of protons, but they have different mass numbers. A nucleus with excess neutrons is unstable and may decay and emit radiation. The chemical behavior of a radioactive isotope is very much like that of the stable isotope. It is detected by an Geiger counter. Radiation can kill you and damage your DNA; cause cancer. Radioactive isotopes are used in medicine. Acts as an tracer. Radioactive isotopes are used in medicine in conjunction with PET(positronic emission tomography) which is used to determine the comparative activity of tissues. Used to treat cancer. |
|
|
The arrangement of electrons, protons, and neutrons: |
Electrons in atoms arrange in orbit around the nucleus of the atoms. This is called its energy shell. The first shell can only contain 2 electrons. Each shell after can contain 8 electrons. |
|
|
What is the octet rule? |
An atom has only one shell, the outer shell is complete when it has 2 electrons. If an atom has 2 or more shells, the outer shell is most stable when it has 8 electrons. Noble gases has 8 electrons in their outer shell. |
|
|
How atoms can be arranged? |
Atoms with fewer than 8 electrons in its outer shell can react with other atoms in such a way that each has a complete outer shell after the reaction. Atoms can give up, share or accept electrons. The group number in the periodic table tells you how many electrons in the valence shells or how many other atoms they can bond with to achieve eight electrons in their outer shell. |
|
|
What is an valence shell? |
The number of electrons in an atom's outer shell. It can determine its chemical reactivity. |
|
|
How do smaller atoms such as carbon bond? |
Smaller atoms can bond with each other and form long chained molecules while large atoms like silicon are unable to bond to other silicon atoms. |
|
|
What is a molecules? |
A group of atoms bonded together. |
|
|
What is a compound? |
A molecule that contains atoms of more than one element. |
|
|
Two types of chemical bonds that contain molecules and compounds: |
Ionic bonds and covalent bonds. |
|
|
What is an ionic bond? |
An electrostatic attraction between oppositely charged ions. |
|
|
What are ions? |
Electron transfer that changes atoms to ions. |
|
|
Things that end in -ide: |
Negatively charged ions. |
|
|
Common ionic compounds: |
Ionic compounds are often found as salts. Can be found either dry solid or in an disassociated form. |
|
|
What is an covalent bond? |
A covalent bond is when two atoms share electrons in order to have a complete outer shell. Covalent bonds are much stronger than a H bond. The large number of H bonds in water makes the H bond strong overall. |
|
|
Things to know about covalent bonds: |
A single atom may form bonds with more than one other atom. |
|
|
Chemical reactions: |
Are important to all organisms. In a chemical reactions the formula will have Reactants Products 6CO2 + 6H20 ------------------------> C6H12O6 + 6O2 The equation is known to be balanced when the same number of each type of atom occurs on both sides of the arrow. |
|
|
Why is water important? |
Most important molecule on earth. All organisms are made up of 70-90% of water. Cells consist of membranous compartments enclosing aqueous solutions. Water has unique properties that make it a life-supporting substance. |
|
|
Structure of water: |
Electrons shared between two atoms in a covalent bond are not always shared equally, due to the atoms difference in their electronegativeity. |
|
|
What is electronegativeity? |
The affinity for electrons in a covalent bond. |
|
|
Electrons and electronegativeity: |
Electrons that are more electronegative tend to hold shared electrons more tightly than those that are not. This cause the bond to become POLAR, meaning that the atoms on each side of the bond are partially charged. Even though the whole molecule itself bears no net charge. |
|
|
Electronegativeity of water: |
Oxygen is more electron negative than hydrogen. Why because the number of protons. The covalent bonds are angled and the molecule becomes shaped as an V. Polarity causes water molecules to be attracted to one another. The positive hydrogen atoms in one molecule are attracted to the negative oxygen atoms in other water molecules. |
|
|
What is a hydrogen bond? |
The attraction where each water molecule can engage in as many as four H bonds. |
|
|
Properties of water: |
Properties of water is due to its polarity and its ability to form H bonds. Properties of water that support life: Solvency Cohesion Adhesion High surface tension High heat capacity High vaporization Varying density |
|
|
What is hydrophilic? |
Molecules that are attracted to water. |
|
|
What is hydrophobic? |
Non-ionized and nonpolar molecules that are not attracted to water. |
|
|
What is disassociate? |
To break up |
|
|
Why NaCl disassociates in water? |
Negative ends of the water molecule are attracted to the sodium ions and the positive ends of the water are attracted to the chloride ions. |
|
|
Solvency of water: |
Water dissolves many polar nonionic substances by forming H bonds with them.
When ions and molecules disperse in water, they move about and collide allowing reactions to take place.
Without dissolving power of water, aquatic organism could not take up the substances they need to from water. |
|
|
What is cellular fluid? |
The aqueous solutions of various substances. |
|
|
Water molecules: |
Are both cohesive and adhesive. Cohesive is the ability of water molecules to cling to each other due to its H bonding. Strong cohesion is due to water being able to flow freely and molecules do not seperate from each other. |
|
|
What is adhesion? |
The ability of water molecules to cling to other polar surfaces. It does so because of water's polarity. The + and - poles of water molecules cause them to adhere to other surfaces. |
|
|
Interesting fact: |
Blood is over 90% water. |
|
|
How water cohesion and adhesion benefit plants? |
Evaporation of water at the leaves is immediately replaced because water molecules are cohesive and tension is created that pulls water up from the roots. Adhesion causes water in plants to keep the water column from breaking apart. |
|
|
High surface tension in water: |
Water molecules at the surface are more strongly attracted to each other than to the air above. Water molecules at the surface cling tightly to each other. The stronger the force between the molecules in a liquid, the greater the surface tension. |
|
|
High heat capacity of water: |
Water can absorb heat without greatlý changing its temperature due to H bonds that link water molecules. High heat capacity is important to aquatic organism and all organisms because the temperature of water rises and falls slowly. High capacity of vaporization in water takes a lot of heat to break a H bond in the water for it to become gaseous and evaportaes into the environmet. Example: in the summer the ocean absorbs and stores solar heat and in the winter it releases it slowly. |
|
|
Density of water: |
Water is less dense than ice. Ice expanding (Freezing) is less dense than liquid and floats. When ice melts in the spring it draws heat from the environment helping prevent a sudden change in temperature that might be harmful to life. |
|
|
What happens when water disassociates? |
It releases an equal number of hydrogen ions (H+) and Hydroxide ions (HO-). |
|
|
Acidic solution: |
Are things such as lemon juice, coffee , tomato juice , etc. They have a sharp sour taste. Often associated with indigestion. Acids substances disassociate in water by releasing Hydrogen ions (H+). A strong acid is dependent on how fully it diassociates in water. When HCl is added to water, the number of H+ ions increases greatly. |
|
|
Basic solutions: |
Are things such as milk of magnesia and ammonia. They have a bitter taste and feel slippery in water. They either take up H+ ions or release HO- ions. A strong base is determined by how it fully it disassociates in water. If HCl is added to water, the HO- ions increases. |
|
|
pH and the pH scale |
pH is the mathematical way of indicating the number of H+ ions in a solution. The pH scale is used to indicate acidity or bascity. The pH scale ranges from 0 to 14. pH 7 is neutral - this includes water, tears , etc At pH 7 H+ and HO- concentrations are equal. pH below 7 is acidic because of H+concentration is greater than HO-. pH above 7 is basic HO- concentration is greater than H+ concentration. Moving along the pH scale from 7 to 0 each unit is 10 times the acidity of the previous unit. Moving from 7 to 14 each unit has 10 times the basicity as the previous unit. |
|
|
What is a buffer? |
A chemical or a combo of chemical that keeps pH within normal limits. To maintain homeostasis in the human body, we need to keep the pH within the body in a narrow range. Buffers resist pH change because they take up excess H+ ions and HO- ions. |
