exam 1 Flashcards
describes how close a measurement is to the true or known value
Accuracy
How well several independent measurements agree with each other
Precision
uncertain digit
last digit
Fahrenheit to celsius formula
(F-32) / 1.8
density of water at room temp?
1.00 g/mL
periods
The horizontal rows
Elements with similar properties are in the same column
group or family
“Z” means
number of protons
“A” means
protons + neutrons
Group 1A
Alkali metals
- Soft, shiny metals
- Are never found in nature in the pure state because they are highly reactive
- Are always found in combination with other elements
Alkali metals
Group 2A
Alkaline Earth Metals
- Lustrous, silvery metals
- Harder and denser than alkali metals
- Reactive, but less than Group 1
Alkaline Earth Metals
- Is a non-metal
- Notice it is located at the top of Group 1A, but it is not part of that group.
- It is the first element of the periodic table because it has the smallest mass
- It is a colorless and odorless gas
- Most abundant element in the universe
- Highly flammable and will burn in air
- It exists in nature as two atoms combined
Hydrogen
- Most important element to sustain life
- Colorless and odorless gas
- It exists in nature as two atoms combined
Oxygen
- Colorless and odorless gas
- It is a liquid when kept under pressure but a gas at room temperature
- Important is many industrial applications, particularly in fertilizers
- It exists in nature as two atoms combined = N2
Nitrogen
- Colorful, non-corrosive non-metals
- All diatomic = meaning 2 atoms F2, Cl2, Br2, I2
- Found combined with other elements in nature
- F2 and Cl2 are gases
- Bromine is a liquid at room temp = Br2 (l)
- Iodine a dark, purple solid at room temp = I2 (s)
Group 7A: Halogens
- Are all gases at room temp
* Very unreactive, practically inert
Group 8A: Noble Gases
- The most stable element form is called white phosphorous
- It exists as four P atoms attached together = P4
- Used in tear gas and explosives
P4, Phosphorous
exists as 8 atoms attached together
• Used in gunpowder, matches, fireworks, and fertilizers
• Yellow solid
S8, Sulfur
Solids at room temperature, except Hg Reflective surface and are shiny Conduct heat Conduct electricity Malleable (can be shaped) Ductile (drawn or pulled into wires)
Metals
Found in all 3 states (s, l, g )
Solids are brittle
Poor conductors of heat
Poor conductors of electricity
Non-metals
Two elements that are liquid in nature
Mercury Hg and Bromine Br
Diatomic elements
HNOF -ClBrI
Ammonia
NH3
Methane
CH4
metals will only become
Cations
non-metals will only become
Anions
water boiling point
100 celcius
