Unit 2 Flashcards
(54 cards)
What is an element
a substance that consists of identical atoms
what is a compound
a pure substance made up of two or more elements in a fixed ratio by mass
what is a mixture
a combination of two or more pure substances
atomic number ( z #)
the number of protons in the nucleus
mass number (A)
the sum of the number of protons and neutrons in the nucleus
properties of a proton
+1 charge
mass = 1.6726 x 10^-24
mass (amu) = 1.0073
in the nucleus
properties of an electron
-1 charge
mass = 9.1094 x 10^-28
mass (amu) = 5.4858 x 10^-4
outside the nucleus
properties of a neutron
0 charge
mass = 1.6749 x 10^-24
mass (amu) = 1.0087
in the nucleus
What are atoms called that have the same number of protons but a different number of neutrons?
isotopes
When something is written like Element - #, what does the number stand for ?
the mass number (protons + neutrons)
how many neutrons are in Oxygen - 16 ?
Oxygen has 8 protons, so 8 neutrons (when answering rewrite with mass number on top, protons on the bottom and the element on the far right.
What is atomic weight?
a weighted average of the masses (in amu) of its isotopes found on earth
What is the bottom number of an element on the periodic table?
the atomic mass (amu)
What is the top number of an element on the periodic table?
the atomic number (Protons)
Which elements occur naturally as only one isotope?
Gold, Flourine, Aluminum
Atomic Radius Trend
the atomic radius decreases going from left to right across a period and increases from top to bottom in a column or family
Ion trend
going from neutral to an anion, the anion will always be bigger
For every unit of negative charge, an electron is ____
gained
For every unit of positive charge, an electron is ____
lost
If elects are in the same family or column they will have similar _____ properties because they have the same number of ____ electrons
physical/valence
Metal properties
- solids at room temperature
- conduct electricity
- form alloys
- give up electro in chemical reactions
Non-metal properties
- on right side periodic table (except Hydrogen)
- doesn’t conduct energy
- accepts electrons in chemical reactions
Metalloid Properties
- mixture of properties from metal and non metals
Distribution of electrons in shells trend
as the shells go from 1-4 the energy increases
