chapter 2 Flashcards
What is matter?
Anything that takes up space and has mass; made of elements
What is an atom?
the smallest unit of matter that still retains the properties of an element
What is an element?
pure substance that cannot be broken down to other substances by chemical reactions
Which four elements make up 96% of human body mass?
C, H, O, N (Carbon, Hydrogen, Oxygen, Nitrogen)
Are there molecules that aren’t compounds? If yes, give an example.
Yes; O2, H2
Are there compounds that aren’t molecules? If yes, give an example.
Yes; NaCl
Neutrons
no electrical charge; part of the nucleus
Protons
positive charge; part of the nucleus, attracts electrons
Electrons
negative charge; orbit the nucleus, attracted to protons
If a normal atom of an element has 6 protons: a) which element is it? b) how many electrons will it usually have? c) how many neutrons will it usually have?
a) Carbon
b) 6
c) 6
How is an element’s atomic number determined?
atomic number = number of protons
How is an element’s atomic mass determined?
protons + neutrons = atomic mass
Describe covalent bonds.
A covalent bond is the sharing of one or more pairs of valence electrons by two atoms.
What do you call compounds that form from covalent bonds?
molecules
How do the properties of polar and nonpolar molecule differ?
Polar = has slight charge at ends of molecule; non-polar = no charge
