Properties of elements and chemical bonds Flashcards
What is the periodic table?
Tabular arrangement of the elements in order of
increasing atomic number
Elements having similar chemical properties are positioned in vertical columns
What are periods?
Horizontal rows of elements
What are groups?
Vertical columns of elements that have similar
chemical properties
What are the Groups with non-numerical names
- Alkali metal (IA)
- Alkaline earth metal (IIA)
- Halogen (VIIA)
- Noble gas (VIIIA)
What are the major elements in the human body?
Hydrogen, carbon, nitrogen and oxygen
what are the macrominerals in the human body?
Na, Mg, K, Ca, P, S, Cl
What are the microminerals (trace minerals) in the human body?
V, Cr, Mn, Fe, Co, Cu, Zn, Si, As, Se, I, Mo
What are the classifications of non metals?
- No metallic luster
- Poor electrical conductivity
- good heat insulators
- brittle and nonmalleable
What are the classifications metals?
- Metallic grey or silver luster.
- high electrical and thermal conductivity
- Malleable and ductile.
What are Metalloids?
- They have some of the properties of metals and some of nonmetals
- Six elements are classified as metalloids: boron, silicon,
germanium, arsenic, antimony, and tellurium.
What are the 4 classification by electronic properties?
Representative elements
noble-gas elements
transition elements
Inner transition elements.
What is an electron shell
Region of space around a nucleus that contains electrons
that:
* Have approximately the same energy
* Spend most of their time approximately the same distance
from the nucleus
* Electrons that occupy the first electron shell are closer to
the nucleus and have a lower energy than electrons in the
second electron shell
What is a chemical bond? and what are the types?
Attractive force that holds two atoms together in a more
complex unit.
Formed as a result of interactions between electrons found
in the combining atoms.
* Ionic bonds
* Covalent bonds
- Polar covalent bonds
- Non polar covalent bonds
What is an Ionic bond?
Formed through the transfer of one or more electrons
from one atom or group of atoms to another atom or
group of atoms
Ionic compound: Compounds in which ionic bonds are
present
What is a covalent bond?
Formed through the sharing of one or more pairs of electrons
between two atoms.
There are two types of covalent bonds:
* Polar covalent bonds- non equal sharing of electrons
* Non polar covalent bonds- equal sharing of electrons
Important Generalizations About Valence Electrons.
- Representative elements in the same group have the same
number of valence electrons - The number of valence electrons for representative elements is the
same as the Roman numeral periodic-table group number - The maximum number of valence electrons for any element is
eight
What are lewis symbols?
are electron dot symbols, representing the
number of valence electrons in an atom
a convenient way to represent the valence electrons, which are shown
as dots placed around the symbol for the element
What is a valence shell and valence electrons?
Valence Shell: The outer most shell of an atom
Valence electrons: The number of electrons in the outer most
shell
Octet rule
Octet rule: The tendency of group 1A-7A elements to react in ways that
achieve an electron configuration of eight valence electrons.
What are the guidelines about Electron Loss and Gain by Atoms of
Elements?
-Metal atoms containing one, two, or three valence electrons tend to lose electrons to acquire a noble-gas electron configuration.
* Nonmetal atoms containing five, six, or seven valence electrons tend to gain electrons to acquire a noble-gas electron configuration
What is an Ion?
Atom (or group of atoms) that is electrically charged as a result
of the loss or gain of electrons
An atom becomes an ion by gaining or losing
electrons. An atom is neutral (has no charge) Positive and negative ions
What is a cation? and examples
Positively charged ion - Atom loses one or more electrons
(Cation) Na+.
Lithium
sodium
potassium
magnesium
have a + on the end of the symbol.
What is an anion?
Negatively charged ion - Atom gains one or more electrons
(Anion) Cl-
Nitride
phosphide
oxide
sulfide
Add ide on the end of the element. will have a - on the end of the symbol
Transition elements
form more than one type of cations. Different naming system is needed for these cations. A roman number is used in brackets, which shows the charge of the ion
Formation of ionic compounds
Ion formation requires the presence of:
A metal that can donate electrons
A nonmetal that can accept electrons
Electrons lost by the metal are the same ones gained by the nonmetal
Positive and negative ions simultaneously formed from an electron transfer attract one another
Chemical formulas for ionic compounds
Ionic compounds are always neutral
* No net charge is present
* Ratio in which positive and negative ions combine is the
ratio that achieves charge neutrality for the resulting
compound
Writing formulas for ionic compounds
Full name of the metallic element is given first. This is followed by a separate word containing the stem of the nonmetallic element name and the suffix –ide
1. Symbol for the positive ions is always written first
2. Charges on the ions that are present are not shown in the formula
3. Subscripts in the formula give the combining ratio for the ions
NaCl MgO KCl CaS Na2O LiBr
what is a covalent bond
A chemical bond resulting from two nuclei attracting the same
shared electrons. Electron sharing produces increased stability
Although all covalent bonds involve sharing of electron pairs,
they differ in the equality of the sharing:
Polarity of Covalent Bonds
Sharing of electron pairs,
* Nonpolar covalent bond: Electrons are shared equally.
* Polar covalent bond: Electron sharing is not equal.
* The equality of the sharing depends on the relative electronegativities of the bonded atoms.
In a polar covalent bond:
* the more electronegative atom attracts the shared electrons more
strongly and acquires a partial negative charge
* the less electronegative atom attracts the shared electrons less
strongly and acquires a partial positive charge
