CHEM 01 3 Periodicity Flashcards
A powerful tool for understanding and predicting the physical and chemical properties of elements
Periodic Table
-The number of protons in the nucleus of the atom
Atomic Number
-The average mass of the atoms in an element
Atomic Mass
-Usually from a Greek or Latin word for the element or a substance containing the element
Element Name
-Short-hand abbreviation for the element name
Symbol
-The person credited the most for the development of the periodic table
-He was not the first scientist who tried to arrange elements in a certain order
-Chemists mostly credit him
-Because he also used chemical properties to organize the table
-He left blanks for future elements
-Elements that would eventually be found
-Predicted some missing elements
Dmitri Mendeleev
-Had the same conclusions as Dmitri Mendeleev
Lothar Meyer
-Dmitri Mendeleev and Lothar Meyer independently came to the same conclusion about how elements should be grouped
True or False
True
-The chemical reactivity of the elements is largely determined by their ….
-Are the outermost electrons
Valence Electrons
-Referred to as core electrons
Nonvalence Electrons
-Going across the periodic table
-Horizontal row
-Elements are arranged in these
Periods
-Going down a column, elements are arranged as these
-Vertical column
-All elements in a given …. Have the same number and type of valence electron
Groups
-The alkali mentals (Group 1A elements) all have the same electron configuration of ns¹
-The all tend to lose one electron to form the unipositive cation
-Hence, they share physical and chemical property
True or False
True
-Are soft, metallic solids
-They are found only in compounds in nature, not in their elemental forms
-Typical metallic properties (luster, conductivity) are seen in them
Alkali Metals
-Have higher densities and melting points than alkali metals
-They readily form +2 cations, losing the 2 valence electrons.
Alkaline Earth Metals
-Are typical nonmetals
-They have highly negative electron affinities, so they exist as anions in nature
-They react directly with metals to form metal halides
Halogens
-Helium and neon are chemically inert (They have desired electrons)
-This lack of chemical reactivity is due to the completely filled ns and np subshells
-A condition that often correlates with great stability: Law of Octaves
-They are found as monatomic gases.
Noble Gases
-Right to Left (Left is more Metallic)
-Top to Bottom (Bottom is more Metallic)
Metallic Character (Direction)
-Most of the elements in nature are these
-The following are some properties these:
-Shiny luster
-Conduct heat and electricity
-Malleable and ductile
-Solids at room temperature (except mercury)
-Low ionization energies/form cations easily
Metals
-Are found on the right-hand side of the periodic table.
-Properties of these include the following:
-Solid, liquid, or gas (depends on element)
-Solids are dull, brittle, poor conductors
-Large negative electron affinity, so they form anions readily
Non-Metals
-Have some characteristics of metals and some of nonmetals
-Several are electrical semiconductors (computer chips)
Metalloids
-Is the repetitive pattern of property for elements based on the atomic number.
-The following properties are discussed in this unit:
-Sizes of atoms and ions
-Ionization energy
-Electron affinity
-Electronegativity
Periodicity
- is a fundamental property that leads to many of the trends
-Many properties of atoms depend on electron configuration and on how strongly the outer electrons in the atoms are attracted to the nucleus
-The attractive force between an electron and the nucleus depends on the magnitude of the nuclear charge
-And on the average distance between the nucleus and the electron
Effective nuclear charge
- It is tempting to think of atoms as hard, spherical objects
-According to the quantum- mechanical model,
-However, atoms do not have sharply defined boundaries at which the electron distribution becomes zero
-Hence, we define the size of an atom in terms of its …
-Which is one-half the distance between the two nuclei in two adjacent metal atoms or in a diatomic molecule
Atomic Radius
-Is the radius of a cation or an anion
Ionic Radius
-Are smaller than their parent atoms
-Removing one or more electrons from an atom reduces electron-electron repulsion but the nuclear charge remains the same
-So the electron cloud shrinks
Cations
-Are larger than their parent atoms
-Because the nuclear charge remains the same but the repulsion resulting from the additional electron(s) enlarges the domain of the electron cloud
Anions
-Group of ions all containing the same number of electrons in an ….,
-The more positive the charge, the smaller the ion
Isoelectric Series
-Is the minimum energy required to remove an electron from the ground state of a gaseous atom or ion
-The first ionization energy is the energy required to remove the first electron
-The second ionization energy is the energy required to remove the second electron
-The higher the ionization energy, the more difficult it is to remove an electron
Ionization Energy
-Is the energy required to remove the first electron
First Ionization Energy
-Is the energy required to remove the second electron
Second Ionization Energy
-Have higher ionization energy values
Smaller Atoms
-Measures the energy change when an atom gains an electron
-Measures the attraction, or affinity
-Of the atom for the added electron
-For most elements, it is negative in value
-Indicates that an atom easily accepts electrons
Electron Affinity
-Is the ability of an atom in a molecule to attract shared electrons to itself
-Elements with higher ……. have a greater tendency to attract electrons than do elements with low …….
Electronegativity
-Elements that exist as individual atoms
-Noble gases
Monoatomic Gases
-Elements that appear in pairs
Diatomic Gases
-An atom having a positive 1 charge that is a cation with +1 charge
-Has donated one of its electrons to form a unipositive cation
-The all tend to lose one electron to form the unipositive cation
-Only one valence electron
Unipositive Cation
-An atom having a negative 1 charge
-Anions with a charge of -1
-Gaining one electron
Uninegative Anion
