Science A Flashcards
Dalton
Analogy: “The Billiard Ball”
- Atoms are the smallest particles of matter + are invisible
- All atoms of the same element are identical but differ from other elements
JJ Thompson
Analogy: “The Rasin Bun”
-Atoms had tiny negatively charged particles (electrons)
(Had theories based on electrons, revised the atomic theory)
Rutherford
Analogy: “nuclear”
Stated most of an atom is empty space but contains particles with a positive nucleus and electrons orbit it (gold foil)
(Discovered that atoms has a dense, positively charged core)
Bohr
Analogy: “A solar system”
-colors of light
Electrons existed in a number of energy levels (orbits nucleus)
Neutrons and protons in the middle, electrons orbit
Heisenberg + Schrodinger
Analogy: “The Cloud”
- Not possible to know the path electrons take around nucleus.
- Quantum Theory
- Mathematical
Democritus
- Ancient Greeks started the idea about atoms
- Democritus proposed that all matter was made of particles that could not be divided
- Called them Atomos (meaning invisible)
Who created the periodic table
Dmitri Mendeleev
Groups, Family, Period
Group/Family = vertical column;
-members have similar chemical properties
Period = horizontal row
Elements are classified by metals and non-metals (bold staircase)
Alkali metals, Alkali earth metals, Halogens, Noble gases
AM- Group 1 or first row on the very left (most reactive)
AEM- Group 2
Halogens - Group 17
Noble gases- Group 18 (least reactive)
Properties of metal vs non-metal
Metals- shiny, ductile, malleable, and heat conductors.
Non-metals- dull, brittle, insulators
Atomic # = Protons (Carbon is #6, so Carbon will have 6 protons)
atomic mass is Protons + Neutrons
How to find out how many electrons are in an atom or ion
In an atom, # of protons = # of electrons
In an ion, look at its charge. We know that the atomic # equals the # of protons. Oxygen has a negative charge of 2, so therefore it will have two fewer protons than electrons. (8 protons because of its Atomic# and it’ll have 10 electrons.)
Isotopes
Atoms of an element that differ in a number of neutrons and atomic mass.
Express uranium 238 in isotopic notation form
238 (atomic mass)
U
92 (atomic #)
Ions
an atom that has gained or lost electrons or has a charge, it is an ion.
If an element loses one or more electrons to become a positively charged ion, it is called a cation.
Elements that gain electrons to become ions are known as anions.
How many electron rings would magnesium have?
3 because its found in period 3
Ionic + Molecular compounds are
When 2 or more different elements chemically
combine/bond a compound is formed.
Ionic is a Cation+Anion, or metal + non-metal.
Also, make sure when writing a compound that the positively charged element goes first.
Ionic compounds
Ionic compounds are crystalline solids at SATP (standard
atmospheric temperature and pressure), have relatively
high melting points, and are good conductors of
electricity
Molecular compounds
Molecular compounds form when 2 or more nonmetallic
atoms share electrons and bond covalently. Molecular compounds may be solid, liquid, or gaseous at SATP, but tend to have relatively low melting points and are non-conductors, with the exception of acids.
Formula for water, ammonia, and hydrogen peroxide
H2O, NH3, N2O2
Buffers
Substances that can act to neutralize both acids and bases in order to minimize changes in pH
Ions have a charge and atoms don’t
hh
Process by which an acid and a base react to form water and salt (produces NaCl + H2O)
neutralization reaction
Why are acidic solutions good conductors of electricity
Because when dissolved in water they form/separate into ions, which are ideal for conducting electricity.
Properties of Acids & Bases
Properties of acid include being sour tasting, electrically conducting when in solution, and turning blue litmus red.
Bases are bitter to the taste, electrically conducting when in solution and turn red litmus blue.
Notice that each change in pH of 1, indicates a 10x change concentration. A change of 2 pH values is 100x different. (READ THIS)
what is the ph of a solution that has a concentration of 1x10 to the power of -4?
pH 4
WHMIS symbols & names
Workplace Hazardous Materials Information System
exploding bomb - for explosive or reactivity hazards
Flame - fire hazards
flame over circle - oxidizing hazards
Gas cylinder - gas under pressure
Health Hazard - may cause health effects
Corrosion (person washing hands) corrosive damage
! - may cause less serious health effects or damage to the ozone layer
Skull and Crossbones - cause death or toxicity
Law of conservation of mass (is reflected by
numbers/coefficients that are written before the
symbols of chemical entities in a chemical reaction
equation. READ THIS)
The total mass of the products is always the same as the total mass of the reactants. It states that matter is not created or destroyed in a chemical.
For example, when wood burns, the mass of the soot, ashes, and gases equals the original mass of the charcoal and the oxygen when it first reacted.
Endothermic vs exothermic reactions
Exothermic - chem reaction that releases heat and energy (cellular respiration)
Endothermic - chem reaction that absorbs heat energy (Photosynthesis)
Because exothermic involves heat, the temp will increase as the reaction proceeds.
Bio chemical reactions
A biochemical reaction is the transformation of one molecule to a different molecule inside a cell. Biochemical reactions are mediated by enzymes, which are biological catalysts that can alter the rate and specificity of chemical reactions inside cells. Examples would be
Reactants and Products
The substance(s) to the left of the arrow in a chemical equation are called reactants. The substance(s) to the right of the arrow are called products.
Radio Isotopes
An unstable form of a chemical element that releases radiation as it breaks down and becomes more stable. Radioisotopes are used in medicine for diagnosis and
treatment of disease. Have an excess number of neutrons
Binary Ionic Compound
Binary Ionic Compounds Containing a Metal and a Nonmetal.
A binary compound is a compound formed from two different elements, a metal and a non-metal. When naming binary ionic compounds, name the cation first (specifying the charge, if necessary), then the nonmetal anion (element stem + -ide).
tetra
4
hexa
6
penta
5
octa
8
hepta
7
deca
10
nona
9
Rule for Significant digits
Zeros used solely for spacing the
decimal point are not significant. The zeros
are place holders only.
– You can tell a number is a placeholder if when you
remove the zeros, the number CHANGES its value
Example:
7000 g - 1 significant digit
0.00783 kg - 3 significant digits
Calculations with significant figures
CALCULATIONS WITH SIG FIGS • RULE: When multiplying or dividing measurements, round off the final answer to the number of significant digits in your measurement having the least number of significant digits Examples: 1. 2.03 cm x 36.00 cm = 73.08 cm² = 73.1 cm² 2. (1.13 m)(5.126122m) = 5.7925178 m² = 5.79 m² 3. 49.6000 cm² / 47.40 cm = 1.0464135 cm = 1.046 cm
