The Science Test

 In the Bohr model there were distinct energy levels where electrons could exist.  1 st energy level holds 2 electrons  2 nd energy level holds 8 electrons  3 rd energy level holds 8 then 18 after 4 th level gets 2 electrons. Oxygen What element is this?

 The atom is mostly empty space  Two regions Nucleus- protons and neutrons. Electron cloud- region where you might find an electron.

LocationMassCharge Outside nucleus in electron cloud electrons nucleus nucleus 1 amu 1 amuNeutralneutrons nucleus 1 amu +1protons

The number of protons in an atom of a particular element is its atomic number. Each element has a different atomic number.

 Protons and neutrons are responsible for most of the atomic mass of an atom.  The number of protons and neutrons in an atom are the mass number of that atom.

9 F Fluorine ,7 Atomic Number Atomic Symbol Element name Atomic Mass Number of electrons per level

For any given element, all nuclei have the same number of protons, but the number of neutrons may vary. These atoms of the same element with different atomic masses are called isotopes.

What is an electron? a. Particle with a + charge b. Particle with a – charge c. Particle with no electrical charge d. The basic building block of an element An atom of neon (Ne) has 10 protons, 10 neutrons, 10 electrons. What is the atomic mass of Ne? a. 0amu c. 20 amu b. 10 amud. 30 amu

 A solution is a homogeneous mixture composed of a solute and a solvent.  A solute is the dissolved substance in a solution. There is less of it. salt in salt water sugar in soda carbon dioxide in soda  A solvent is the dissolving medium. You have more of it. water in salt water water in sodas

 An electrolyte is a substance whose water solution conducts electricity.  ionic compounds such as NaCl (sodium chloride  acids and bases such as HCl (hydrochloric acid) and NaOH (sodium hydroxide)  Non electrolytes are substances whose aqueous solutions do not contain ions and do not conduct an electrical current.

State MovementProximityShape/Volume Solid Very little; slow Tightly packed Definite shape and volume Liquid Free to move; faster Close together No definite shape; definite volume Gas Very fastVery far apart No definite shape; fills container

 Plasmas consist of freely moving charged particles, i.e., electrons and ions.  Lightning creates a jagged column of plasma.  When an electric current is passed through neon gas, it produces both plasma and light.  Part of a comet's streaming tail is plasma from gas ionized by sunlight and other processes.  The Sun is a ball of plasma.

Vinegar is a solution of two liquids: water & acetic acid. Most vinegar contains 95% water & 5% acetic acid. In vinegar, acetic acid is ___. a. A solventc. an element b. A mixtured. solute Salad dressing often contains vinegar & oil. Shaking a bottle of dressing combines the ingredients, but afterward the vinegar & soil separate. Which term describes the salad dressing? a. Solutionc. heterogeneous mixture b. Soluted. homogeneous mixture

 Alpha decay- consists of two protons and two neutrons  Beta decay-released electron  Gamma decay- high-energy photon

 Alpha  Beta  Gamma

The time it takes for half of a radioactive element to decay is its half-life.

What type of nuclear reaction results in a single nucleus undergoing a decrease in mass number, a decrease in atomic number and the release of a helium nucleus? a. Alpha decay b. Beta decay c. Gamma decay d. Chemical reaction How much would remain after one half-life if you started with 24 grams of the substance? a. 24 gramsc. 12 grams b. 48 gramsd. 124 grams