Chapter 2-4 Flashcards
Give an example of an overlap of chemicals and biology.
− Duroia hirsuta trees are known as “devil’s garden” due to the lack of other plants that surround them.
− It was discovered that ants living in these trees release a chemical known as formic acid into intruding plants to provide space for the Duroia hirsuta tree that serves as their home
What is matter?
Matter- anything that takes up space and has mass
What is an element? How many elements are there?
Element- a substance that cannot be broken down by a chemical reaction
• Chemists recognize 92 elements
What is a compound?
Compound- substance consisting of two or more different elements combined at a fixed ratio
• A compound has characteristics different than those of its elements
How many elements are essential to life?
25
Which elements make up 96% of all living matter?
Carbon Oxygen Hydrogen Nitrogen
What are trace elements and what is an example?
Trace elements- elements required by an organism in minute quantities (less than .01% body weight), iodine prevents goiter
List the trace elements.
Trace Elements: boron cobalt copper chromium fluoride iron iodine manganese molybdenum selenium silicon tin vanadium zinc
List the major minerals.
Elements that make up 4% of an organisms weight (major minerals): sodium potassium chloride calcium phosphorus magnesium sulfur (salty potato chips contain pretty much salt)
What is an atom?
Atom- the smallest unit of matter that still retains the properties of an element
What are subatomic particles?
Subatomic particles- protons (+), neutrons (0), electrons (-)
How are the subatomic particles structured in an atom?
Protons and neutrons are packed together in a tight core or atomic nucleus and electrons form a negative cloud around the nucleus
What units are used to compute the mass of an atom?
Daltons or atomic mass unit (amu) are used to compute the mass of an atom. One neutron or proton is about one Dalton or amu. (electrons are ignored when computing mass)
What is the atomic number?
Atomic Number- number of protons (if neutral this equals the number of electrons)
What is the mass number?
Mass Number- sum of protons and neutrons
What is atomic mass?
Atomic Mass- precise mass in Daltons
What is an isotope?
atoms with different amounts of neutrons
What is a radioactive isotope?
Radioactive Isotope- an isotopes in which the nucleus decays spontaneously giving off particles and energy (Carbon 14)
What occurs when a radioactive isotope lead to a change in the number of protons?
When the decay lead to a change in the number of protons it transforms to an atoms of a different element (radioactive carbon to nitrogen)
What are the uses and consequences of radioactive isotopes?
- PET scans use radioactive isotopes and are also used in dating fossils
- Radiation from decaying isotopes poses a hazard to life by damaging cellular molecules
Which subatomic particle is directly involved in reactions between atoms?
electrons
What is energy?
the capacity to cause change
What is potential energy?
energy that matter possesses because of its location or structure
How do electrons have potential energy?
Electrons of an atom have potential energy because of how they are arranged in relation to the nucleus- the more distant an electron is from the nucleus the greater its potential energy
What are electron shells?
Electrons are found in different electron shells- each with a characteristic distance and energy level
What occurs when an electron absorbs or loses energy?
- When an electron absorbs energy it moves to a shell farther out from the nucleus (light may excite an atom)
- When an electron loses energy it falls back to a shell closer to the nucleus and lost energy is usually released to the environment as heat
How many electrons can each shell hold?
• First electron shell can only hold 2 electrons and the second 8, and the third 8.
What is the chemical behavior of an atom most dependent on?
The chemical behavior of an atom depends mostly on the electrons in the outermost shell. Valence electrons and valence shell.
What is an atom with a full valence shell called?
• Helium, neon, and argon have full valence shells and are celled inert or inactive.
What is an orbital?
• Orbital- three dimensional space where an electron is found 90% of the time
> Such as s, p, and d
> S is spherical and P is dumbbell shaped
> No more than two electrons can occupy a single orbital
What are chemical bonds?
atoms sharing or transfer valence electrons
What is a covalent bond?
Single/ double?
Covalent Bond- the sharing of a pair of valence electrons by two atoms
• A single bond is a pair of shared electrons while a double bond is two pairs of shared electrons
What is valence?
Valence- the bonding capacity of an atom- usually equals the number of unpaired electrons required to complete the atoms outermost electron shells
What is electronegativity?
Electronegativity- the attraction of a particular kind of atom for the electron of a covalent bond
What is a non-polar covalent bond?
electrons are shared equally
What is a polar covalent bond? Give an example?
− Polar covalent bond- electrons shared unequally- water is polar
• Oxygen is more electronegative and is partially negative charged (-)
• Hydrogen is less electronegative and is partially positively charged (+)
What is an ionic bond?
Ionic Bond- transfer of electron from one atom to another- NaCl
What is an ion? And what are the two types?
Ion- a charged atom- charge can be found by protons-electrons
• Cation- positive charge
• Anion- negative charge
What are compounds formed by ionic bonds called?
Compounds formed by ionic bonds are called ionic compounds or salts. They aggregate and form crystals in nature.
How does the environment affect ionic bonds?
Environment affects ionic bonds. Dry salt crystals are strong, while salt crystals dissolved in water are weak
What is a hydrogen bond?
Hydrogen Bond- hydrogen atom covalently bonded to one electronegative atom is also attracted to another electronegative atom H2O and NH3
What are Van Der Waals interactions?
−Electrons are not always symmetrically distributed and at any instant they accumulate by chance in one part of the molecule. This results in ever-changing regions of positive and negative charge that enable all atoms and molecules to stick to one another in van der Waals interactions.
Allow geckos to walk up walls
Why does molecule shape impact function?
− Molecular shape impacts function because only molecules with complementary shape can form weak bonds with each other.
What is a chemical reaction?
the making and breaking of chemical bonds
What are the component of a chemical reaction?
products and reactants
What is chemical equilibrium?
the point at which chemical reactions offset each other exactly
What is the photosynthesis reaction?
− 6 CO2 + 6 H2OC6H12O6 + 6 O2
4 reasons water is relevant.
- ¾ of Earth’s surface is submerged in water
- Water is the only common substance to exist on Earth in all three physical states of matter
- All life is tied to water.
- Humans need water and cells are 70-95% water.