Ch.2 Flashcards
Law of conservation of mass
Antonine Lavoisier-
The physical law that matter is neither created nor destroyed in a chemical reaction.
When a chemical reaction occurs, the total mass of the substances involved in the reaction does not change. 
Law of definite proportions
Joseph Proust-
A law stating that all samples of a given compound (Regardless of their source or how they were prepared) have the same proportions of their constituent elements.
For ex:
Decomposition of 18.0 g of water results and 16.0 g of oxygen and 2.0 g of hydrogen, or an oxygen-to-hydrogen mass ratio of:
16.0 g O
Mass ratio = _____________ = 8.0 or 8:1
2.0 g H
Law of multiple proportion
John dalton-
A law stating that went to elements (A and B) form two different compounds, the masses of element B that combined with 1 g of element A can be expressed as a ratio a small whole numbers. 
Dalton already suspected that matter was composed of Atoms, so that went to elements, A and B, combine to form more than one compound, an atom of A combined with either one, two, three, or more atoms of B (AB1, AB2, AB3, etc). Therefore, the ratio of masses of B that reacted with a fixed mass of A would always be a small whole number.
Atomic theory:
That each element is composed of tiny indestructible particles called Atoms, that all Atoms of a given element have the same mass and other properties, and that atoms combine and simple, whole number ratio is the form compounds.
1. Each element is composed a tiny indestructible particles called Atoms.
2. All Atoms of a given element of the same mass and physical/chemical properties that distinguish them from other atoms of other elements.
3. Atoms combined in simple hole number ratio is the form compounds.
4. Adams of one element cannot change into Atoms of another element. In a chemical reaction, Atoms only change the way that they are bound together with other atoms. 
Electrical charge
A fundamental property of certain particles that causes them to experience a force in the presence of electrical fields.
Results in attractive and repulsive forces—called electrostatic forces— between those particles. 
The area around a charged particle where these forces exist is called an electrical field.
•Positive and negative electrical charges attract another.
•Positive charges repel another.
•Negative charges repel one another.
•Positive and negative charges of exactly the same magnitude sum to zero when combined. (+1 + (-1) = 0)

Electron
A negatively charged, Low-mass particle found outside the nucleus of all Atoms that occupies most of the atoms volume but contributes almost none of it’s a mass.
Mass
Charge x ———— = mass
Charge
Nuclear Theory 
The theory that most of the Adams mass and all of its positive charge are contained in a small, dense nucleus.
- Most of the Atom’s mass and all it’s positive charge are contained in a small core called the nucleus.
- Most of the volume of the Atom is empty space, throughout which tiny, negatively charged electrons are dispersed.
Protons and atomic number (Z)
A positively charged subatomic particle found in the nucleus of an atom.
The number of protons in the nucleus is known as the atomic number and is given the symbol Z. The atomic number defines the element. 
Neutrons
An electrically neutral subatomic particle found in the nucleus of an atom, with a mass almost equal to that of a proton. 
Isotope
Atoms of the same element with the same number of protons but different numbers of neutrons and consequently different masses.
Natural abundance
The relative % of a particular isotope In a naturally occurring sample with respect to other isotopes of the same element.
Mass number
The sum of the number of protons and neutrons In an atom. Symbol A:
A = # of protons (p) + # of neutrons (n)
A mass #
X chemical symbol
Z atomic #
Ion
An atom or molecule with a net charge caused by the loss or gain of electrons.
The charge of an ion depends on the relative number of protons and electrons and as indicated in the upper right corner of the symbol. 
Cation
A positively charged ion. (electron removed)
Anion
A negatively charged ion. (Electron added)
Atomic mass
The average mass in u of atoms of a particular element based on the relative abundance of various isotopes; it is a numerical equivalent to the mass and grounds of one more of the element
Sometimes called atomic weight, average atomic mass, or average atomic weight.
Atomic mass = sum of n (fraction of isotope n x mass of isotope n) = (fraction of isotope 1 x mass of isotope 1) + (fraction of isotope 2 x mass of isotope 2) + ….
