Presentation on theme: "Atom P’s, N’s and e’s oh please!!. Two regions Nucleus and the electron cloud. The nucleus in located in the center of the atom with an overall positive."— Presentation transcript:
Two regions Nucleus and the electron cloud. The nucleus in located in the center of the atom with an overall positive charge. The electron cloud surrounds the nucleus and it has an overall negative charge.
The three particles Electron, Proton, and Neutron The electron is found in the electron cloud, it is very small in mass (to the point that it is normally a negligible amount). The charge direction is negative. The charge value is 1.6022*10 -19 C
The proton is found in the nucleus. It has a positive charge direction. Its charge value is 1.6022*10 -19 Its mass is approximately 1 amu. An amu is atomic mass unit. The neutron is found in the nucleus. It has no charge. Its mass is approximately 1 amu.
Atomic Number (Z) It is the smaller, whole number in a square on the periodic table for one element. It states the number of protons.
Mass number (A) The mass number is the larger number with a decimal. The number states the total number of protons and neutrons the average atom of that element has. The definition of an element is determined by the number of protons.
To determine the number of neutrons, you need to do a little subtraction. First round the mass number to the nearest whole number (because you either have a proton or neutron or you do not) Mass Number (A) – Atomic Number (Z) = neutrons
Practice! How many protons and neutrons does Ca (calcium) have? Mass number is 40 Atomic number is 20 40-20 = 20
Practice Individually Finding Protons and Neutrons Mg Mn
Mg 24-12 = 12 Protons are 12 (because of the atomic number) Neutrons are 12 (because of the subtraction)
Mn Atomic number is 25 Mass number rounded is 55 25 protons 55-25 = 30 neutrons
Electrons To determine the number of electrons, you need to know if you have a charged atom (it is an ion) or a neutron atom. If it is neutral, then protons = electrons.
Neutral Ca 20 protons from its atomic number (Z) Therefore it has 20 electrons
Write the symbol When you write the atomic symbol you do the following
Ions An ion is a neutral atom which has gained or lost an electron. If an atom has an extra electron (or one more electron then it has protons), what do you think happens to the overall charge? It will become negative by one, because electrons have a negative charge.
When an atom has a negative charge it is known as an anion. What happens if the atom has one less electron then it has protons? The atom will have a positive change (it has more protons which are positive then it has negative electrons). This is known as a cation.
So Ca looses two electrons, what will be the resulting charge? +2 What if N gained three electrons? -3
How to determine the number of electrons with a charge? Look at the number of protons it has. Then if it is positive, subtract that positive charge from the protons and that is how many electrons are left. Ca has a +2 charge, it has 20 protons, so it would have 20-2 = 18 electrons.
ElementProtonsNeutronsElectronsCharge 15 Mo As Na0 O-2