Biology 100 Unit 2 Flashcards
what are the building blocks of matter? They can not be broken down into smaller components
Chemical elements
How many elements occur naturally?
92
Biology begins at the _______ level and work toward organismal level
atomic level
something that occupies space and has mass is called
matter
On earth matter exists in three physical states
solid, liquid, gas
What lists all elements in an order based on certain characteristics
The Periodic Table
What elements make up 96% of the weight of the human body?
O, C, H, N
What occur in small amounts but are necessary for life?
Trace Elements
How many elements are essential for life
About 25
A ________ is formed when two or more atoms join together chemical
Molecule
A ________ is a molecule that contains at least two different elements
Compound
A _______ is the smallest unit of matter
Atom
Atoms are constructed of
Protons, Nutrons, and Electrons
positively charged has mass
Protons
no charge, has mass
Nuetrons
negative charge, no mass
Electron
Protons and Nuetrons reside in the
Nucleus
A _____ is an atom’s central core
Nucleus
The electrons reside and orbit in
Electron Shells
The _____ is the number of protons, it determines the element
atomic #
The ________ of an atom is the sum of the protons and the nuetrons
mass #/ atomic mass
Elements are classified by _______________________
the number of protons and nuetrons in nucleus
forms of an element with different mass
- The protons and electrons remain the same
- Nutrons skew
Isotopes
spheres which orbit the nucleus and carry electrons l
Electron Shells
Electrons on the outermost shells determine the atom’s ________
properties
essentially when atoms change electron configuration
Chemical Reactions
Atoms may give up o aquire electrons to satisfy or fill their outer electron shells
- 2 electrons for inner shell
- 8 electrons for outer shells
What are the two types of bonds
- ionic
- covelent
When an atom changes its normal number of electrons it takes on an
electric charge
Charged atoms are called
Ions
Adding an electron gives a
Negative charge
Losing an electron gives a
Positive Charge
Ions are charged because
they have a different number of protons than nuetruns
are formed between oppositely charged ions
Ionic Bonds
positively charged ions
Cations
Negatively Charged ions
Anions
A covelent bond formes when two atoms ______________________
share one or more pairs of outer-shell electrons
In chemical reactions:
- starting material
- ending material
Reactants, Products
How is the earth dependant on water?
- Cells: modern life remains tied to water
- Cells are composed of 70-80%
What has key characteristics such as
surface tension, melting, freezing, evaporation, condensation, specific heat, atomic configuration
Two hydrogen atoms and one oxygen atom are joined by single covalent bonds
2 covelent bonds
an atom that exerts more attraction on electrons is
more electronegative
Unequal electron sharing makes water
polar
Electrons orbit around Oxygen the majority of the time, making the
Oxogen portion partially negative
Tiny polar molecules acting as tiny magnets
Hydrogen bond
Hydrogen bonding’s property that allows water molecules to hold together
Cohesion
ex: water transportation in plants
Water has a lower density in ________ form which is why ice floats
liquid
a liquid in which two or more substances are evenly mixed
Solution
the dissolving liquid is called the
solvent
the dissolving substance is called the
solute
a solution with water as the solvent is called an _________ solution
aqueous
an ________ forms when a chemical compound donates H+ ions to a solution PH: low 0-6
Acid
a _______ forms when a chemical compound removes H+ and adds OH- to the solution PH: High 8-14
Base
the unit we use to measure the relative amount of H+ ions in the solution
PH
help our body stabalize PH
Buffers
