semester exam Flashcards
why do elements chemically combine?
And how are they different afterwards
Elements chemically combine to achieve noble gas configuration acc to the octet rule.
Theyre different after because they become stable
What are anions
Anions are ions that are negatively charged
what are cations
Cations are ions that are positively charged.
If a balanced atom loses one or more electrons, it will become a positively charged cation.
what are ions
Ions are charged atoms or molecules.
Which types of elements are more likely to form an ionic bond? Why?
Metals and nonmetals because
the easiest way for metals to achieve a noble gas configuration is to lose electrons,
the easiest way for nonmetals to achieve a noble gas configuration is to gain electrons.
for ionic bonds, how do you write the formulas/figure them out
Write the charges first and then the amount of elements (crossover method) and cation first, anion second
properties of ionic compounds
Crystalline solids at room temperature, brittle (meaning it will break or shatter), easily dissolve in water, bad conductors at room temperature but excellent in liquid or dissolved form
- What are covalent bonds and which type of atoms form them?
Covalent bonds are compounds composed of molecules formed between two nonmetals that shares electrons, and can be solid liquid OR gas
why aren’t structural diagrams used for ionic compounds?
Structural diagrams arent used for ionic compounds because they aren’t molecular compounds and completely transfer electrons
how to determine names for covalent bonds and compounds
First word uses prefix (but if its one, we don’t use the prefix mono) and second etc. also uses prefix
what is the vsper theory? Be able to predict the shape of simple covalent compounds.
valence shell electron pair repulsion;
pairs of electrons are areas of negative charge which repulse each other meaning that as long as you know how many areas of electrons you have on the central atom you can predict the shape.
Edg and molecular shape is how you know the shape
o What is Electronegativity?
A measure of an atoms ability to attract electrons.
How do Electronegativities help predict bond type? what are polar and nonpolar covalent bonds?
The atom with the higher electronegativity holds the bonding electrons more closely, but does not remove them completely
When the electronegativity of two bonding atoms is very similar, neither atoms wins the tug of war and the electrons are shared is a covalent bond
A polar covalent bond occurs when two atoms share electrons unequally
o What are some periodic trends in Electronegativities?;
As you go left to right it gets higher
As you go up from the bottom it gets higher
Highest electronegativity is in top right
How do you determine if a molecule is polar?
To be a polar molecule you have to have at least one polar bond and be asymmetrical
What is metallic bonding
Metallic bonding: metals are held together by metallic bonds and contain loosely bound valence electrons that are passed back and forth between all metal atoms – called sea of electrons
Metals are good conductors bc the electrons are alr moving
All the mobile electrons result in lots of different light and electron interactions– high luster
