Chemistry Outline Notes Flashcards
(45 cards)
What is a chemical reaction? (Definition and examples)
A molecular change of matter that is not always reversible and in which something new is being produced. Ex: Burning gas in a car, taking a tums, a nail rusting.
What is a physical change? (Definition and examples)
A change in the state of matter, usually reversible. Ex: painting a fence, making a milkshake, making a popsicle.
Definition of matter and the two types of changes.
Anything that takes up space. The two types of changes are physical and chemical.
What is all matter composed of? What are the three parts to this?
Atoms. The three parts: protons, neutrons, and electrons.`
What is the nucleus? What are the charges and weight of the particles that make up the nucleus?
The nucleus is the center of an atom, containing positively charged protons and neutrally charged neutrons, each weighing about 1 amu (atomic mass unit).
Electrons: weight, charge, etc.
Electrons are negatively charged and weigh almost nothing- about 1/1000 of an amu. Electrons take up the most space of any atomic particle.
What do electrons orbit in?
Energy levels, aka electron clouds or orbitals.
How many electrons can the first energy level hold? The second? The third?
1st: 2. 2nd: 8. 3rd: 18, but it is electrically stable with 8.
Atomic number
The number of protons. This can also be used to determine the number of electrons, because a regular atom with a neutral charge has an equal number of protons and electrons. The atomic number is unique for every element.
Atomic mass number
Number of protons+number of neutrons. It indicates how much mass the atom has.
CHNOPS
Carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur. These naturally occurring elements are essential for life.
If H (hydrogen) weighs 1 amu and has 1 proton, how many neutrons does it have?
0.
All naturally occurring elements are____ in charge.
Neutral. This is why the number of protons would equal the number of electrons.
What are isotopes and what can they be used for?
They are atoms that differ in their number of neutrons. They are unstable and can release small amounts of energy in the form of radiation. We can use them to date fossils and in medicine as tracers.
Valence electrons
Electrons on the outermost energy level. When drawing a molecule, it is only necessary to include the outermost energy level. Atoms chemically react to fill their outermost shell and therefore become stable.
Is hydrogen stable? Why or why not?
It is not stable because its outermost ring can hold 2 electrons but only has one. It wants to gain one more electron.
Atoms join to become stable. What is it called when 2 or more atoms join together?
Molecules.
What forms when atoms join to keep them together?
Chemical bonds.
How does hydrogen gas form?
2 hydrogen molecules want their outermost ring to be full, so they both want to gain one more valence electron. They share electrons.
The bond in which electrons are shared?
Covalent bond.
The bond in which electrons are moved or taken?
Ionic bond. The connection is formed because the atom that gives away its electron now has a positive charge, and the atom that gains an electron has a negative charge. The opposite charges attract.
What does the law of conservation of mass and energy state?
Mass and energy are neither created or destroyed, they just change form.
How many molecules are there in 3 NaCl? How many Na atoms and Cl atoms are there?
3 molecules of NaCl (sodium chloride: table salt), 3 atoms of Na and 3 atoms of Cl.
2 H2 +O—> 2H2O. Explain this and whether it follows the law of conservation.
Two molecules of hydrogen gas (four atoms total of hydrogen) plus one oxygen atom equals two molecules of water-four hydrogen atoms and TWO oxygen atoms. The law is not followed because the total amount of atoms changes- you would need another oxygen atom in the reactant (totaling 2) to get the two oxygen atoms in the product.
