Ar
Protons and electrons are represented by this
Atomic Number
The original 4 elements in alchemy
Fire, water, earth, air
Change: chopping wood
Physical change
These subatomic particles have a negative charge
Electrons
On a Bohr drawing, this many electrons can fill the 2nd shell
8
Why the alkali metals are so reactive
Only one valence electron
The most stable of the families.
Noble gases
Valence electrons
When 2 elements are joined together, such as O2 or CO2
Molecule
The number of electrons that can be held in shells 1, 2, and 3- not the total, but on each shell
Shell 2- 8 electrons
Shell 3- 18 electrons
Change: digesting pasta
Chemical change
These two elements are liquid at room temperature.
Mercury (Hg) and bromine (Br)
A chemical reaction that emits (gives off) heat.
Exothermic
Sum of protons and neutrons equals
Atomic mass
Property: luster and ductility
Physical
This type of group straddles the staircase.
Metalloids
Potassium (K) is part of this highly reactive group.
Alkali metals
Important metal for electrical wiring.
Copper
International system to ensure workers are safe when using hazardous materials, made up of different symbols.
WHMIS
When 2 different elements are joined, such as CO2 or H2SO4
Compound
The symbol for Argon
Ar
This number (and 2 examples) of elements that are gas at room temperature
12: He, N, O, F, Ne, Cl, F, Ar, Kr, Xe, Rn, Og
Opacity
The element count in this compound:
2H2SO4
Hydrogen- 4
Sulphur- 2
Oxygen- 8
A chemical change that absorbs heat (feels cool or cold)
Endothermic