Matter & Classification
What are the three states of matter?
Solid, liquid, gas
What three particles make up an atom?
Protons, neutrons, electrons
What is electronegativity?
The ability of an atom to attract electrons in a bond
What is the different between ionic and covalent bonds?
Ionic = transfer of electrons (metal + nonmetal)
Covalent = sharing of electrons (nonmetal + nonmetal)
How many valence electrons does oxygen have?
6
What is the difference between an element and a compound?
Element = one kind of atom
Compound = two or more kinds of atoms bonded together
Which particle determines the identity of an element?
Protons
Which element has the highest electronegativity?
Fluorine (F)
Give an example of an ionic compound.
NaCl, MgO, etc.
Draw the Lewis structure for H2O.
Give an example of a heterogeneous mixture.
Ex. Salad, sand and water, cereal with milk
What is an isotope?
Atoms of the same element with different numbers of neutrons
Why does atomic radius decrease across a period?
Increasing nuclear charge pulls electrons closer
What type of bond is formed between two nonmetals?
Covalent
Non-polar, linear shape cancels dipoles
What is a pure substance?
A substance made of only one type of particle (element or compound)
What is the difference between atomic number and mass number?
Atomic number = protons
Mass number = protons + neutrons
Which has a larger atomic radius: Na or Cl? Explain.
Na (father left, larger radius)
A bond where electrons are shared unequally
Draw the Lewis structure for NH3.
H-N-H with one lone pair on N, plus one more H
Is salt water an element, compound, or mixture? Explain why.
Mixture. It contains water and salt (two different substances)
Calculate the number of neutrons in an atom of chlorine-37.
37-17=20 neutrons
Na, Mg, Al, Si (increasing across period)
Explain why NaCl is ionic but CO2 is covalent.
NaCl is metal + nonmetal (ionic)
CO2 is two nonmetals (covalent)
Bonds are polar, but tetrahedral shape cancels dipoles which make it be a non-polar molecule.