Unit 3 Test Flashcards
Is water a polar or a nonpolar molecule? Why?
Water is a polar molecule because the protons in the oxygen nucleus pull the negative electrons closer to the oxygen end of the molecule, giving it partial negative charge. The hydrogen end of the molecule becomes partially positive because the hydrogen protons are “sticking out.”
What happens when a polar and nonpolar solution are combined?
Polar and nonpolar solutions do not mix.
What is electronegativity and what is it used for?
Electronegativity is the ability of an atom to attract electrons when the atom is in a compound. It’s used for measure the tendency of an atom to attract bonding pair electrons.
How do you know the number of valence electrons in an atom?
The valence electrons are the same as the elements group number.
What types of elements are in group 1 and 2 on the periodic table?
The elements in group 1 and 2 are metals.
What type of element is hydrogen?
Hydrogen is a nonmetal.
Are there any polyatomic cations?
Yes, these are ammonium and hydronium
What are valence electrons?
Valence electrons are electrons in the highest occupied energy level of the element’s atoms.
What subatomic particle determines an element’s chemical properties?
Valence electrons determine the atom’s chemical properties.
When are roman numerals used?
Roman numerals are used when writing formulas for transition metals.
What does the octect rule have to do with noble gases?
The goal of the octect rule is to obtain the electron configuration of noble gases because they are stable.
What does the charge on an ion represent?
The charge determines whether the ion is positive or negative. If an ion gains electrons it becomes more negative, while if it loses electrons it becomes positive.
What does the octect rule state and how does it apply to ionic versus covalent compounds?
The octect rule states that in forming compounds, atoms tend to achieve the electron configuration of a noble gas. In ionic compounds it exchanges electrons while it shares electrons in covalent compounds.
what is a salt?
Salt is a chemical compound of sodium and chlorine.
what type of ions end in –ide?
Ions that end in –ide are anions.
what are the elemental characteristics of ionic compounds compared to covalent compounds?
Ionic compounds are a mix of metals and nonmetals. Covalent compounds consist of 2+ nonmetals.
what is the definition of ionic bond?
An ionic bond are electrostatic forces that hold ions together. They are used to create stable octects.
how do you know the charge of a transition metal from the formula?
To find the charge of a transition metal from the formula you use the reverse criss-cross method.
how can you differentiate between a polar covalent and nonpolar covalent bond?
A polar covalent bond electronegativity ranges from .4-1.9 while nonpolar covalent is 0-.4.
which intermolecular force affects the surface tension of a substance?
Hydrogen bonds affect the surface tension of a substance
What is a polyatomic ion? What makes it different from an ion?
A polyatomic ion is a tightly bound group of atoms that have covalently bonded positive/ negative charge and behaves as a unit. What makes it different from a regular ion is because it is covalently bonded.
What types of molecules have Greek prefixes in their names?
Molecules that are criss-crossed and covalent formulas have Greek prefixes in their names.
List all the differences between ionic and covalent compound including their chemical properties (melting points, conductivity, solubility)
Ionic compounds have high melting points, conduct electricity when dissolved in water, and are soluble in polar substances. An example of a ionic compound is salt. Meanwhile, covalent compounds have a low melting point, do not conduct electricity, and are soluble in non-polar substances. An example is sugar.
Where are cations vs anions on the periodic table?
Cations are found on the left side of the table in comparison to anions being found on the right.
what does it mean when an anion ends -ate or –ite?
When an anion ends in –ate or –ite, it determines how many subscripts it has.
How can an acid be identified by its formula?
Based on how an acid is named, it can determine what kind of ion it is. For example, Nitric acid is nitrate and hydrogen. This is because the –ic means the anion ends in –ate.
When is the prefix hydro- used as opposed to the ending -ic or -ous in naming acids?
The prefix hydro- is used when the anion ends in –ide. In other words, it is not a polyatomic ion.
define ion
when atoms tend to gain/lose electrons based on how many valence electrons they have // atoms or groups of atoms that have a positive/negative charge
define cations
(+) ions that have lost electrons, has more positive protons than negative electrons (metals)
define anions
(-) ions that have gained electrons has more negative electrons than positive protons (nonmetals)
define polar molecules
when one end of the molecule is slightly negative and the other end is slightly positive, this creates a dipole
define intermolecular forces / van der waals and name the 3 forces
- weaker than ionic/covalent bonds
- determine whether a compound is a solid, liquid, or gas
- the 3 forces that fall under this category are dipole, interactions, dispersion forces, and hydrogen bonding
define dipole interactions
polar molecules are attracted to one another, creates cohesion among the molecules
define dispersion forces
extremely weak due to the movement of electrons in a molecule, the more electrons a molecule has = greater dispersion forces
define hydrogen bonding
the attractive forces - almost bonding - between Hydrogen atoms of covalent moleculesand an unshared electron paurs of another atom. This creates surface tension
name 2 qualities of a polar molecule
- asymmetrical electron distribution
- geometrical symmetry
covalent bonds have more or less electronegativity
less
true or false: a dipole movement is required for a polar molecule
true
where do cohesive molecules pull molecules
inward
define halide ions
ions produced when atoms of chlorine and other halogens gain electrons
-all have 7 v.e. and only need one more to achieve an electron configuration of a noble gas
define diatomic molecule
molecule consisting of 2 molecules
define single covalent bond (same with double and triple covalent bond)
2 atoms that are joined by sharing a pair of electrons
EX: H-H
define coordinate covalent bond
covalent bond in which 1 atom contributes both bonding electrons
define bond disassociation energy
energy required to break 2 covalently bonded atoms
define nonpolar covalent bond
when atoms in a bond pull equally
define polar covalent bond
covalent bond between atoms in which the electrons are shared unequally ; the more electronegative atom attracts electrons more strongly and gains a slightly negative charge
define dipole
molecule with 2 poles
