Term
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Definition
Is anything that occupies space and has mass (weight).
•Matter is composed of 92 naturally-occurring elements |
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Term
| What forms can matter take? |
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Definition
Matter is found in three states
1. Solid – rocks, you and me
2. Liquid – water
3. Gas – air |
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Term
Define element.
****Note element, atom, & molecule are interchangable terms. |
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Definition
Is a substance that cannot be broken down to simpler substances that are different.
•An element is a substance that cannot be broken down to simpler substances that are different
•Each element is known by its name (usually Latin) and a 1 or 2 letter abbreviation |
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Term
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Definition
Is the smallest unit of an element.
****Note element, atom, & molecule are interchangable terms.
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Term
| Name the 4 atoms make up 96% of the weight of an organism. |
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Definition
1. Carbon
2. Hydrogen
3. Nitrogen
4. Oxygen
****In order from most to least as it relates to the quantity in the human body. |
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Term
| Name the 3 subatomic particles that atoms are composed of and the arrangement of the particles in an atom, and the charge of each. |
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Definition
3 subatomic particles
1. Protons are positively charged.
2. Electrons are negatively charged.
3. Neutrons are electrically neutral.
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Term
| The arrangement of subatomic particles in an atom. |
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Definition
1. # Protons = # Neutrons = # Electrons.
2. The nucleus is the small, dense region in the center of the atom consisting of protons and neutrons (in clusters).
3. Electrons occupy shells outside nucleus.
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Term
How is the atomic number of an atom determined? |
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Definition
The atoms are numbered in the periodic table for the number of protons they have.
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Term
How is the atomic mass of an atom determined? |
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Definition
Atomic mass = protons and neutrons (combined together).
•Each atom has mass called atomic mass
•Atomic mass of an atom depends on the number of subatomic particles
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Term
Why don’t electrons contribute to atomic mass? |
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Definition
Electrons - do not contribute to the atomic mass because it does not have any mass or weight enough to contribute. |
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Term
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Definition
Atoms of the same element that have different number of neutrons
•Isotopes are occur naturally in nature
* Sometimes have an extra neutrons. |
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Term
Can isotopes be of benefit? |
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Definition
1. Can be used as tracers to follow chemical processes in the body.
2. Mutagenic – cause damage to the DNA in cells.
Define: The isotopes behave chemically just like the “normal” element but because we can detect the energy given off by the isotopes, we have found ways to use them.
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Term
Why do electrons “stay” in their shells around the nucleus? |
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Definition
•Electrons are attracted to the positive nucleus
–Revolve around nucleus in orbitals or shells
•It takes energy to keep the electrons in their shells
–Each shell has different energy levels
–Outermost shell = valence shell
•The valence shell is important because it will determine the chemical properties the atom will have |
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Term
Know the octet rule and how the electrons are ordered around the nucleus. |
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Definition
•Atoms are most stable when their valence (outer most) shell has 8 electrons
•Atoms want to try to add electrons or loose electrons to have 8 in the valence shell
•Number of electrons in outer shell determine the chemical properties or reactivity of the atom
–If 3 or less – Tendency to donate electrons
–If 5 or more – Tendency to receive electrons
•Atoms that donate or receive electrons create compounds and molecules in chemical reactions |
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Term
What particle of an atom participates in chemical bonds? |
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Definition
Electrons
•Number of electrons in outer shell determine the chemical properties or reactivity of the atom
–If 3 or less – Tendency to donate electrons
–If 5 or more – Tendency to receive electrons
•Atoms that donate or receive electrons create compounds and molecules in chemical reactions |
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Term
Know the difference between a compound and a molecule. |
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Definition
•Molecules are substances consisting of two or more atoms of the same element
•Compounds are substances consisting of two or more atoms of different elements
********NOTE: Terms are often used interchangeably molecules & compounds. |
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Term
Know what a chemical formula tells you. |
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Definition
•Compounds and Molecules have chemical formulas which indicate the atoms and the number of atoms that they are comprised of.
–Shows each element symbol and the number of each |
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Term
Know the types of chemical bonds discussed in class and how each is formed. |
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Definition
Chemical Bonds
C6H12O6: Is one molecule.
C6 = indicates 6 atoms of carbon.
H12 = indicates 12 atoms of hydrogen.
O6 = indicates 6 atoms of oxygen.
•REMEMBER:
•Number of electrons in outer shell determine the chemical properties or reactivity of the atom
–If 3 or less – Tendency to donate electrons
–If 5 or more – Tendency to receive electrons
•Atoms that donate or receive electrons create compounds and molecules in chemical reactions |
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Term
What does it mean when a molecule is polar and non-polar? |
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Definition
•The atoms of covalent bonds do not always share the electrons equally.
–Nonpolar – equal sharing of electrons.
–Polar – one atom attracts electrons to a greater degree
•Nonpolar molecules (no “+” or “-” parts) dissolve only slightly or not at all in
water.
–Hydrophobic
•Polar molecules have “+” and “-” parts and easily dissolve in water because water has “+” and “-” parts
–Hydrophilic
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Term
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Definition
Water is a polar molecule.
•Oxygen is a HUGE atom with 8 protons
•Hydrogen is tiny with 1 proton
•Electrons spend more time around the oxygen nucleus
•The oxygen side has a “-” charge
•The hydrogen sides have a “+” charge
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Term
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Definition
•Acid: substance that dissociates in water and releases H+ ions
–Increases the number of H+ ions in the solution
–Ex: HCl → H+ + Cl- |
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Term
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Definition
•Base: substance that either takes up H+ ions or releases OH- ions
–Ex: NaOH → Na+ + OH- |
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Term
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Definition
•Because of the changes in pH can affect living organisms metabolism there are substances that resist changes in pH
–Helps keep pH in “normal” range
–Work by taking up excess H+ or OH- ions
•Our blood: pH ~ 7.4 – changes can be life threatening
–pH: 7.0 = acidosis
–pH: 7.8 = alkalosis |
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Term
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Definition
Buffering System in Our Blood
•Components: carbonic acid, bicarbonate
–Helps keep pH in “normal” range
–Work by taking up excess H+ or OH- ions
•Both are in the blood:H2CO3 H+ + HCO3-
•When H+ added to blood: H+ + HCO3- H2CO3
•When OH- added to blood: OH- + H2CO3 HCO3- + H2O
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Term
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Definition
•The number of electrons per shell is:
–1st electron shell = 2 electrons
–2nd electron shell = 8 electrons
–3rd electron shell = 18 electrons
•Always start with the innermost shell! |
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Term
Define solution, solvent and solute.
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Definition
Water is a Solvent
Solutions consist of:
–A solvent = fluid – usually water
–A solute = what you want to dissolve |
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Term
| Importance of Water in Biology & It's properties |
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Definition
•All chemical reactions occurring in an organism – occur in water
•Properties of Water
–Solvent
–High heat capacity
–High heat of evaporation
–Cohesive and adhesive
–Density
–Dissociation
•These properties are a result of the hydrogen bonding between the water molecules
Liquid Water
•Water is a liquid because of the hydrogen bonding between the water molecules
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Term
| Are element and atom interchangeable terms for this class? |
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Definition
| Yes, per Professor Sak for the purpose of this class element and atom are interchangeable terms. |
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Term
When does radioactive occur? |
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Definition
When the element wants to eject the extra neutrons which releases radioactive, which can cause problems.
* Which is called decaying, which is getting rid of the extra neutrons. |
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Term
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Definition
** Is caused by isotopes that spontaneously decay.
As the isotope decays it gives off energy in the form of rays and subatomic particles which can be detected in a number of ways. |
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Term
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Definition
Molecules of hydrogen or oxygen form when 2 identical atoms combine chemically.
When 2 atoms of hydrogen combine with 1 atom of oxygen, the compound water is formed.
****Example of a Compound
*Table Salt or sodium chloride
- equal parts of sodium (Na) & chlorine (Cl)
****** Characteristics dramatically different than the elements that they are made up from |
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Term
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Definition
Are Electron donor and electron acceptor.
Ions = giving and taking of electron creates charged atoms.
Ionic bond = attraction between two ions.
•Ionic compounds dissociate in water
***An Ionic bond is a "give and take" followed by the attraction or positive and negative. |
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Term
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Definition
1. Sharing of electrons
- Both atoms get "full" outer shell - at least 8 electrons.
2. Atoms can share multiple pairs of electrons
- Double bond
- Triple bond
Ex.) Negatively chargerd electron is H20
H20 - can break down almost anything, except oil has no positive or negative side.
Without a pos/neg elements cannot dissolve in H20. |
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Term
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Definition
•Electronegativity: ability to attract electrons
–Depends on number of protons!
–More protons = more positive charge = stronger “pull” on the negatively charged electrons
–Electrons will spend more time around the atom with the larger number of protons. |
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