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Atoms and Elements
- An atom is the smallest particle of any element, which is a pure form of matter.
- Atoms can be broken down into subatomic particles: protons, neutrons, and electrons
- An atom is made up of an electron cloud around a nucleus
- Electrons constantly moving around the nucleus make up the cloud, protons and neutrons clumped together make up the nucleus
- Protons and neutrons are make up of smaller particles called quarks
- In a neutral atom, the number of protons = the number of electrons = the number of neutrons.
- Electrons in the electron cloud have different amounts of energy. The model of electron configuration places electrons in seven energy levels.
- The electrons in energy levels closest to the nucleus have less energy than those electrons in levels further from the nucleus.
- Electrons fill the energy levels from the inner levels to the outer levels.
- Inner levels are completely filled with 8 electrons before electrons are placed in the next level out. The first level is filled at 2 electrons.
- The atomic number gives the number of protons in one atom of the element.
- ISOTOPES are atoms of the same element that have different numbers of neutrons.
- Isotopes are named with the
symbol and the mass number.
MASS NUMBER is the sum of protons and neutrons in an atom.
A solute and a solvent combine to make a (1,0)20.
Solution
What type of mixture is a solution?
A homogeneous mixture.
What do you call a solution when water is the solvent?
An aqueous solution
What can you do to a chunk of rock salt in order for the salt to dissolve faster?
Heat, crush, and/or stir.
Changing the solutes, solvents, temperature or pressure will affect the (1,0)20 of a solution.
Solubility
Which solution has a higher concentration: 2 L of water combined with 20g of salt or 2L of water combined with 40g of salt?
2L of water with 40g of salt
If a substance has a pH of 6, is it an acid, a base, or neutral?
The substance is a weak acid
What is formed in the chemical reaction between an acid and a base?
Salt and water
Why does water make an excellent solvent?
The slight charges that exist in polar molecules of water help to attract tiny pieces of the solute and allow them to break off from the solute faster (dissolves faster)
Liquid mercury is dissolved by solid sodium to form a solution. Identify the solute and the solvent.
Mercury is the solute and sodium is the solvent.
*These practice questions are only helpful when you work on them offline on a piece of paper and then use the solution steps function to check your answer.
Answer
Atoms and Elements
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