What is the most common/stable ion of magnesium?
Mg2+
Which two subatomic particles have an approximately equal mass?
Protons and neutrons weigh about 1 amu
What is the most common/stable ion of chlorine?
Cl1-
What is matter?
Anything that has mass and volume
How many protons does sulfur have?
Sulfur's atomic number is 16, so it has 16 protons
The periodic table is organized by...
Increasing atomic number
What is the difference between an element and a compound?
Elements are composed of one type of atom, compounds two or more types of atom
How many energy levels does phosphorus have?
Phosphorous (P) is in period 3, so it has 3 energy levels
Explain why a state of matter change is a physical change
Physical changes result in a decrease, increase, or spread of molecules. For example, when ice melts into water, the H2O molecules do not change.
Which element is brittle at room temp: Potassium, Calcium, Sulfur, Gold, Aluminum
Sulfur, because it is a nonmetal. We saw this in the metals, nonmetals, metalloids lab.
In a chemical change, what happens to the organization of the atoms?
Chemical bonds between atoms are broken and new bonds form. Atoms rearrange.
Who discovered that elements always combine in the same ratios (the Law of Constant Composition)?
John Dalton
What did the gold foil experiment prove?
Atoms are mostly empty space, with a small, dense, positively-charged center
Metal alloys are... elements, compounds, homogenous mixtures, or heterogenous mixtures?
Homogeneous mixtures. The metals are not bonded together
What is another name for a homogenous mixture?
A solution
Draw a particle diagram of the sublimation of CO2
Compound should show two distinct atoms. Sublimation is solid --> gas. Solid is in orderly rows, gas takes up space
What is the most common isotope of silicon?
Silicon-28
Which is a chemical change: boiling water, dye + water, rust, paint chipping
Rust is a chemical change. The color changes and you need a chemical process to reverse it.
How many electrons does a neutral atom of calcium have?
Calcium's atomic number is 20, so it has 20 protons. A neutral atom has the same number of protons and electrons, so 20.
True or false: Elements can be atoms OR molecules?
True. Some elements bond with themselves in nature (like O2), some elements exist as single atoms (like Ne)
Which family of elements is most electrically conductive?
Metals
Why does argon not react with other elements?
Ar is a noble gas. Noble gasses have a full valence shell, so they are energetically stable
What did JJ Thompson discover?
The electron, using the cathode ray tube experiment
Why does sulfur form an anion with a charge of 2- ?
Sulfur has 6 valence electrons, so it wants two more to fill its valence shell
How many valence electrons does oxygen have?
Oxygen (O) is in group 16, so it has 6 valence electrons
List 3 signs of a chemical change
Heat, light, color change (usually), bubbles, new substance
In a physical change, what happens to the organization of the atoms?
Structure of the element or compound stays the same. Spacing increases as energy of particles increases.
Hydrogen has three isotopes. H-1 abundance: 99.98%. H-2: 0.012%. H-3: 0.008% Calcuate avg atomic mass.
To find: sum the mass of each isotope * it's abundance. (1)(0.9998) + (2)(0.00012) + (3)(0.00008) = 1.0002
Which is a chemical change: chopping wood, leaves changing color, increasing temp of solution, distilling gasoline
Leaves changing color. The chlorophyll molecules break down into component elements.