Chem Review

Empirical Formula

The chemical formula which shows the relative numbers and types of atoms in a compound in the simplest whole-number ratio. For example, the empirical formula of glucose is CH2O.

if they have similar electronegativity values and also if both are non-metals

How can you tell if two atoms will form a covalent bond?

Balanced chemical reactions relate reactants and products in terms of moles; however, it is impossible to measure substances in moles in the lab. We must convert moles to grams to be able to weigh out appropriate amounts of substances for our chemical reactions in the lab. We will use the molar mass for our conversion factor and set the conversion

How is the molar mass of a compound used in the lab

you must convert from moles of the compound to moles of the element in which you are interested. Then, you must covert from moles of this element to atoms using Avogadro's number.

How many atoms of hydrogen are there in 2 moles of CH2O?

2 - because the subscript next to H is 2

How many atoms of hydrogen are there in one molecule of water? How can you tell?

grams

If the question asks for the mass of carbon in one mole of compound rather than in one molecule the answer will be the same number, but the unit will be

increases as principle quantum number increases

periodic trend of shielding effect

Atomic Radius

the distance from the nucleus of an atom to its outermost electrons. being the size of the atom

Avogadro's number

6.022 X 1023, is the number of particles present in 1 mole of any substance.

mass divided by volume

Density equals __________

Calculate Molar Mass

You must take the sum of the total mass of each element in one mole of the compound.

Nonmetals

form anions

Metals

form cations

diatomic molecules

hydrogen, nitrogen, oxygen, and the halogens, fluorine, bromine, chlorine, and iodine.

cation

positively charged ions.

increases as you move from right to left and from top to bottom on the periodic table.

Periodic trend of atomic radius

increases as you move from left to right and bottom to top on the periodic table.Fluorine has the highest electronegativity

Periodic trend of electronegativity

Valence Electrons

29. Which specific subatomic particles account for the chemical reactivity of the element

physical change

A change of matter from one form to another without changing the substance. Examples include tearing or breaking, boiling, melting, any change of state.

chemical change

A change that occurs when one or more substances change into entirely new substances with different properties.

Molecular Formula

A chemical formula which shows the number and types of atoms actually present in a molecule of a compound as it would actually exist in nature. For example, the molecular formula of glucose is C6H12O6.

atomic mass unit

A unit of mass used to describe the mass of atoms and molecules. One amu is equal to 1/12th the mass of a carbon-12. The mass of a proton is approximately one amu. The mass of a neutron is also close to one amu.

All matter is composed of small particles called atoms. Atoms of a given element are identical in size, mass, and other properties; atoms of different elements differ in size, mass, and other properties. Atoms cannot by sub-divided, created, or destroyed. Atoms of different elements combine in simple whole-number ratios to form chemical compounds. In chemical reactions, atoms are combined, separated, or rearranged.

Dalton's Atomic Theory

Accuracy

Describes how close a measured value is to the true value

Precision

Describes how close several measured values are to each other, the exactness of a measurement.

covalent bonding

involve the sharing of electrons between two atoms in a bond. The mutual attraction of the nucleus of each atom for the shared electrons will keep the atoms bound together

Anion

negatively charged ions

increases as you move from left to right and bottom to top on the periodic table.

periodic trend of ionization energy

shielding effect

refers to the interference of non-valence electrons in the strength of attraction between the positively charged nucleus of an atom and its valence electrons.

method for balancing chemical equations

First, list the different elements and number of atoms of each present on the reactant side of the equation. Second, list the different elements and number of atoms of each present on the product side of the equation. Third, balance the number of atoms of each element present on either side of the equation by adjusting only the coefficients. Do not adjust the subscripts. Finally, recheck to make sure all elements are present in balanced amounts.

equal to the number of protons present in an element

Given the numbers of each subatomic particle in an atom of a specific element, how would you determine the atomic number

equals to the balance of the charges of protons and electrons in the element

Given the numbers of each subatomic particle in an atom of a specific element, how would you determine the charge of that element

equal to the number of protons plus the number of neutrons present in an element

Given the numbers of each subatomic particle in an atom of a specific element, how would you determine the mass number

The Gold foil experiment

Rutherford launched alpha particles at thin layers of gold foil. He expected particles to pass through undeterred, but some were deflected straight back. This meant that particles encountered a dense, positively charged core within the atoms of the gold foil. Rutherford called this core the nucleus.

Subscripts

The small whole number to the right of each element in a compound which tells you the number of atoms of that particular element present in that compound.

Coefficients

The whole number which appears in front of a formula in a chemical equation. This number tells you the number of moles of that substance which are participating in a balanced chemical reaction.

The Lewis structures of diatomic hydrogen and each of the diatomic halogens should show a single covalent bond. The Lewis structure of diatomic oxygen should show a double bond, and that of diatomic nitrogen should show a triple bond.

What would the Lewis Structures of diatomic molecules look like

Determine the total mass of one specific element in a compound

You must take into consideration both the number of the element of interest in the compound which will be designated by the subscript as well as the mass of each atom of that element. For example, if we wanted to know the total mass of carbon in one molecule of glucose (C6H12O6), we would multiply the number of atoms of carbon (6, as indicated by the subscript) times the mass of each carbon atom (12 amu, as indicated by the mass number on the periodic table. The total mass of carbon would be 6 atoms X 12 amu = 72 amu.

a. For ionic compounds, name the cation first using its elemental name from the periodic table. Then name the anion, but replace the ending with -ide. For example, NaCl is sodium chloride. b. For covalent compounds, take the same approach and then add Greek prefixes to indicate the specific number of atoms of each element present in the molecule. For example, CCl4 is carbon tetrachloride. If there is only one of the first element, do not use mono- to start the name; however, you must use the appropriate prefix to indicate the number of the first element in cases where there is more than one atom of that element. Greek prefixes are as follows: 1-mono, 2-di, 3-tri, 4-tetra, 5-penta, 6-hexa, 7-hepta, 8-octa, 9-nona, 10-deca.

basic nomenclature rules for simple ionic and covalent compounds

cathode ray

consists of a stream of electrons (electricity) passing through a gas filled glass tube from one electrode to another. J.J. Thomson discovered

the flame test

can be used to determine the identity of an unknown substance because all elements and compounds have unique emission spectra. The emission spectrum of an element consists of characteristic wavelengths of light released when excited electrons lose energy to return to their low energy ground state

Predictions about element given group

element given only its group number because elements within a group have similar physical and chemical properties. One reason for this is that they have the same number of valence electrons.

Mendeleev

grouped elements according to physical and chemical characteristics. His periodic table was organized by increasing atomic mass.

by balancing the charges of the ions involved in a bond. Do this by finding the least common multiple of the charges of the elements involved, and making the number by which you must multiply each the subscripts in the formula unit.

how you would determine the formula unit of an ionic compound

Mosely

invented the atomic number of elements. His periodic table organized elements according to atomic number. This is how today's periodic table is still organized.

Ionization energy

the amount of energy which must be expended to remove an electron from an element in a gaseous state. More energy will be required to remove electrons from elements which hold onto their electrons tightly. The less shielded the nucleus, the greater the attraction between the nucleus of the atom and its electrons, and the more energy that will be required to remove them

Electronegativity

the measure of the ability of an atom to attract electrons in a bond.