Unit 1: Matter, Chemical Trends, and Bonding Flashcards
What are the 3 ways of representing an element?
Example: Sodium
(23 is the mass number and 11 is the atomic number)
1) 23
Na
11
2) Na- 23
3) Sodium - 23
What do “A” and “Z” represent?
A= Mass Number
Z= Atomic Number
When given that Potassium has 19 protons and 20 neutrons how would you determine A and Z?
Z= 19 (Atomic Number/ Number of Protons)
A= Z + N = 19 + 20 = 39 (Atomic Mass)
Isotope
An element which has the same number of protons in all its other forms but a different number of neutrons. They have the same chemical properties but their physical appearance differs. ( Same Z; Different A)
What is Heavy Water? What is it’s chemical formula?
Water that contains hydrogen in the form of deuterium.
D2O
Mass Spectrometer
A device used to determine the atomic mass and relative abundance of each isotope present in an element.
amu
Atomic Mass Unit
Radio Isotopes
Isotopes and are unstable and decay emitting radiation as their nucleus changes.
What are the 3 types of radiation, their speed, their penetration distance, and an example of an effective barrier?
1) Alpha Slow, A few cm, and a sheet of paper
2) Beta Fast, A few m, 1-2mm of metal
3) Gamma Very fast, unlimited, 1m of lead or concrete
Alpha Particles
A particle composed of 2 protons, 2 neutrons and equivalent to a helium nucleus with a charge of 2+.
Beta Particles
A high energy electron with a charge of 1-.
What is the concept of Half- Life?
The time taken for half of a radio active atoms to decay in a radioactive substance.
What is the concept of Carbon- 14 Dating?
The measurement of a ratio of Carbon- 14 to Carbon- 12 to determine how long and organism has been dead. They compare the normal ratio of a living organisms to a dead one to find the time that has elapsed.
What happens when the amount of Carbon-14 in a sample becomes very small?
The Carbon-14 dating method becomes less reliable.
What other method can be used to date non-living materials? What is it’s half life?
Potassium-40 is used to date objects too old to be effectively dated by the carbon-14 method. It’s half life is 1.3 X 109 years.
What happens to the alkali metals as their atomic number increases?
The elements are more reactive.
What is Atomic Radius? List the 2 Facts you need to know about what it does and why it does them.
One half the distance between the nuclei of 2 atoms of the same element.
1) Decreases from left to right across each period on the periodic table. -The atomic number increase by 1 for each element- therefore increasing by 1 proton as we move right. - The attraction between the nucleus and valence electron increases pulling the electron in tighter. (Radius smaller)
2) Increases from top to bottom down each group on the periodic table - The number of valences increases as we go down a group - More valences means more of a shield to attract the valence electrons to the nucleus.
What is Ionic Radius? List the 2 facts you need to know about Cations and Anions in terms of their atomic radius.
Cations: 1) Ionic Radius becomes smaller across a period/ row - As a cation looses electrons the ionic radius decreases - The attraction of the electrons to the nucleus increases across a period/ row - The nucleus would be able to pull the electrons closer to the nucleus
Anions: 1) Ionic Radius Increases across a period/ row - When gaining an electron the repulsion among electrons increases while nuclear charge remains the same - Nucleus will not be able to pull the electrons as close to the nucleus - They fill the outer shell therefore radius becomes larger
What is Ionization Energy?
The amount of energy required to remove an electron from an atom or ion in the gaseous state.
What is the Difference between First Ionization Energy and Second Ionization Energy?
First Ionization Energy: The amount of energy required to remove the most weakly held electron from a neutral atom
Second Ionization Energy: The amount of energy required to remove a second electron from the gaseous positive ion
What is Multiple Ionization Energies?
After the first electron is removed the valence shell hets a little closer to the nucleus (Increse in effective nuclear charge) It will now take more energy to remove the 2nd electron.