1. Atomic Composition Unit 3 – Atomic Structure Mrs. Callender

2. Write down three things you know about the atom.

3. ELECTRON e- Negatively Charged Atomic Mass – 0.0005 amu Basically round to zero amu 3 Major Subatomic Particles

4. PROTON p+ Positive Charge Mass of 1.007 amu Found in nucleus of atom

5. Neutron n o No charge - “neutral” Mass of 1.0009 amu Found in Nucleus

6. Other Subatomic Particles

7. Computer Generated picture of two bombarded atoms.

8. Symbol -Z All atoms of the same element have the same number of protons in the nucleus. ATOMIC NUMBER = NUMBER OF PROTONS

9. Symbol -A Mass comes from the nucleus of the atom. Mass number = # protons + # neutrons

10. No overall Charge Number of protons and electrons are the same

11. Ion There was either: 1. Gain of electron(s) 1. Loss of electron(s) X+X+ X-X-

12. METALS LOSE ELECTRONS BECOMING POSITIVELY CHARGED. NONMETALS GAIN ELECTRONS BECOMING NEGATIVELY CHARGED.

13. Example Using the Bohr Model Na is a metal and wants to lose an electron so it has a full energy level of electrons. Cl is a nonmetal and wants to gain and electron so it can have a full energy level. 1s 2 2s 2 2p 6 3s 1 1s 2 2s 2 2p 6 3s 2 3p 5

14. Example Using the Bohr Model 11 protons and 10 electrons make an ion with a +1 charge. 17 protons and 18 electrons make an ion with a -1 charge. 1s 2 2s 2 2p 6 1s 2 2s 2 2p 6 3s 2 3p 6

15. How do we write all of this information? Complete Chemical Symbol Write the symbol for the atom with 28 protons, 28 electrons and 31 neutrons. Ni 1. Look up the symbol by using the number of protons. REMEMBER: the number of protons is the same as the atomic number. 2. Write the number of protons in the lower left hand side of the element. 28 3. Add the # of neutrons to the number of protons. REMEMBER - this is the atomic mass. 59 4. Check to see if you have an atom or an ion. If the number or protons does not equal the number of electrons then you will need to add a + charge or a – charge.

16. How do we write all of this information? Complete Chemical Symbol Write the symbol for the ion with 8 protons, 10 electrons and 8 neutrons. O 1. Look up the symbol by using the number of protons. REMEMBER: the number of protons is the same as the atomic number. 2. Write the number of protons in the lower left hand side of the element. 8 3. Add the # of neutrons to the number of protons. REMEMBER - this is the atomic mass. 16 4. Check to see if you have an atom or an ion. If the number or protons does not equal the number of electrons then you will need to add a + charge or a – charge. -2

17. How do we write all of this information? Complete Chemical Symbol Write the symbol for the ion with 20 protons, 18 electrons and 20 neutrons. Ca 1. Look up the symbol by using the number of protons. REMEMBER: the number of protons is the same as the atomic number. 2. Write the number of protons in the lower left hand side of the element. 20 3. Add the # of neutrons to the number of protons. REMEMBER - this is the atomic mass. 40 4. Check to see if you have an atom or an ion. If the number or protons does not equal the number of electrons then you will need to add a + charge or a – charge. +2

18. How do we write all of this information? Element name – atomic mass How many protons, neutrons and electrons are in Tantalum-181. 1. The number of protons comes from the atomic number. 2. The number of electrons equals the number protons because this is a neutral atom. Protons – 73 Electrons – 73 Neutrons – 108 3. The number of neutrons is equal to the mass number minus the atomic number.