Chapter 1 Flashcards
Theory
A hypothesis that has been proven by experiments
Atom
Smallest possible particle of a substance atomos meaning “uncuttable”
Molecules
A combination of two of more atoms held together in a specific shape by attractive forces.
Element
Substance that contains only one type of atom
Compound
A chemical compound Is a substance that contains more than one element.
Give an example of a Chemical Formula
Ex. H2O
Metals
All elements in the left and central region of the periodic table are metals (except for hydrogen).
Good conductors of heat and electricity, malleable and ductile.
All metals are solid at room temperature (except Mercury = liquid)
Non-Metals
Found in the upper right corner of the periodic table. Most non-metals are poor conductors of electricity and heat.
Metalloids
There are six elements that are classified as metalloids (B, Si, Ge, As, Sb, Te). These lie along a diagonal cutting across the table between the metals and the non-metals.these dull appearing, brittle solids and sometimes called semi-conductors, they conduct electricity better than nonmetals, but not as well as metals.
Mixture
Contains two of more chemical substances
Homogeneous
All parts of a sample have the same composition
Pure elements and pure chemical compounds are homogeneous.
A homogeneous mixture is called a solution
Solution
A homogeneous mixture
Heterogeneous
When the composition varies from place to place
Ex. Quartz a chemical compound of silicone and oxygen with a vein of gold.
Chemical transformation
Produces a new substance
Hypothesis
A prediction that must be confirmed.
Precision
Exactness of a measurement
Accuracy
How close a measurement is to the true value
Sig Fig Rules
- nonzero digits are significant
- zeros between nonzero digits are significant
- zeros at the end of a decimal number are significant
- all digits in coefficient of a number in scientific notation are significant
- leading zeros are not significant
- zeros used as placeholders in measurements without decimal points are not significant
Why does ice float in water?
Ice floats in water because ice is less dense than liquid water. Molecules are packed more orderly and symmetrically in ice than liquid water.
This is not true for all substances!
Element with Non-English Roots
Antimony Sb Copper Cu Gold Au Iron Fe Lead Pb Mercury Hg Potassium K Silver Ag Sodium Na Tin Sn Tungsten W
Solid
Definite volume
Definite shape that cannot easily be changed
A condensed phase
Molecules move slowly
Liquid
Definite volume
No definite shape (takes the shape of the container)
A condensed phase
Molecules move slowly
Gas
No constant volume
No specific shape: expands or contracts as its container expands or contracts
Molecules move quickly
Precision
Exactness of a measurement
