Notes of Chapter 17 and 19

Section 1

1. C
Al
H
O
Na

2.Proton, +1, nucleus
neutron, 0, nucleus
electron, -1, electron cloud outside the nucleus

3. Atoms are the smallest particle.In the 5th cent. B.C. the Greek philosophers Democritus and Leucippus proposed that matter was made up of tiny, indivisible particles they called atom, or in Greek "a-tomos". Thereason why they assumed this is because nothing can come from nothing. Around 1803, John Dalton (1766-1844) developed the first useful atomic theory of matter. He imagined the atom as asphere full of an electrically positive substance mixed with negative electron.

4. The blade of the fan spines so fast that you can see through it.
The atoms move fast that theyare like a blur.


Section 2

1. Its atomic number is 17 and its atomic mass is 35.4527
2. Alike: in most chemical properties
Different: the atomic mass variation of coursemeans a difference in weight, but in some extreme cases, some isotopes can be stable while others are radio-active, and will thus turn into other elements over time. Nuclear propertiesare thus different, and some physical properties, like boiling and fusing point, will differ slightly.
3. The mass of a proton or a neutron is almost equal to 1 amu. This is not acoincidence-the unit was defined tht way. The atomic mass unit is defined as one-twelfth the mass of a carbon atom containing six protons and six neutrons.
4. By subtracting 19 (atomicnumber of Potassium) from 40. You should come out with 21, which is the number of neutrons in potassium-40



Section 3

1. Your first step is to find a periodic table. Secondstep is to look at it. (Many periodic tables have a key explaining what information is contained in each box of the tale. I recommend you use a periodic table with such a key.)
2.