Chapter 1: Science & Measurement Flashcards
Chemistry
The study of the composition, structure, and properties of matter and of the energy consumed or given off of when matter undergoes a change
Matter
anything that occupies space and has mass (everything)
Pure Substance
has constant composition; cannot be broken down by a physical process (ex. elements and compounds)
Elements
pure substances that cannot be decomposed into other substances by ordinary means* (found on periodic table)
*by processes that are not chemical (heating, cooling, etc)
Atoms
smallest representative part of an element
-> unique to specific element
size: ~10 ^-10 m
Compound
pure substance that is composed of 2 or more elements bonded together in fixed proportion that can be broken down to those precursor elements by some chemical process (reaction)
->ionic
ex. Na+Cl2=NaCl
Ions
certain compounds that consist of positively or negatively charged particles
Cations
Positively charged
-> Na+, Ca2+, Fe3+
Anions
Negatively charged
->Cl-, SO4^2-, PO4^3-
Molecule
a collection of atoms chemically bonded together in characteristic proportions
-> smallest representative unit of a compound
-> covalent
Diatomic Elements
elements that exist as molecules (7)
H2, Br2, O2, F2, I2, N2, Cl2
“H Bro FinCl”
ALWAYS written as this unless stated otherwise
How to represent molecules?
- Chemical Formulas (H2O)
- Structural Formulas (drawn on paper)
- Ball and stick models (3D)
- Space Filling Models (more accurate)
3 States of Matter
Solid: particles in fixed pattern but vibrate, definite shape and volume
Liquid: particles are close together but arranged randomly and are free to move, indefinite shape, definite volume
Gas: Particles are far apart, move at high speeds, indefinite shape and volume
Precursor
one of the compounds that participates in a chemical reaction that produces another compound
