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