The number of protons in an atom. Is the unique identifier of an element.
plural of nucleus
what does the nucleus contain?
protons and neutrons
The most discreet particle of matter that cannot be broken down further. Contains a positively charged nucleus with negatively charged electrons floating around it. The majority of atoms is empty space.
anything that has mass and occupies space
the scientific method
1. Make observations/collect data 2. Formulate hypothesis 3. Test hypothesis
1. Theory 2. Law
a tested hypothesis that has been proven true - it gives an overall explanation of natural phenomenon
a summary of behavior - a generally observed behavior
units of mass
K(kelvin), Celsius, Fahrenheit
unit factor method
divide measurements by unit factors for conversion
K = C + 273.15
C = K - 273.15 or (Tf - 32DF)5/9 = Tc
Tf = Tc * 9/5 +32
Density = Mass/Volume or g/cm^3
States of Matter
Liquid, Solid, Gas
Properties of Matter
combination of variable composition of pure substances
pure substance that can't be broken down further
combination of elements Ex: H2O
Law of Conservation of Mass
Mass is neither created nor destroyed.
Law of Definite Proportion
A given compound always contains the same proportion of elements by mass. Example: Water is always H2O. It is never something like H2O2.
Law of Multiple Proportions
When two elements form a series of compounds the ratio of masses is always reduced to a series of small whole numbers.
Dalton's Atomic Theory
1. Each element is made up of tiny particles called atoms.
2. Atoms of the same element are always identical.
Different gases contain the same number of particles in the same volume, pressure or temperature.
Dense center of an atom that is positively charged. Contains the majority of the mass of an atom.
Negatively charged, not in the nucleus. Has a mass close to zero.
Positively charged, in the nucleus. Has a mass close to one.
Neutrally charged, in the nucleus. Has a mass close to one.
Atom with a different number of neutrons but the same number of protons and electrons.