Matter Unit Learning Goal #5: Compare the different number of protons, neutrons, and electrons of an atom in terms of ions, isotopes, and compounds.

Structure of An Atom

Remember… Atomic Number is the number of protons in an atom. The number of protons equal the number of electrons in a neutral atom. Atomic Mass is the sum of the protons and neutrons in an atom. 6p + + 6n 0 = 12 (atomic mass of carbon)

Ions A charged entity. This occurs if the number of electrons do not equal the number of protons. This only occurs when an electron is added or removed from an atom. The number of protons never change.

Ions An atom will gain or lose electrons to become more stable.

Cations cation – ion with a positive charge. If a neutral atom loses one or more electrons it becomes a cation. Na 11 protons 11 electrons Na + 11 protons 10 electrons

Anions ion with a negative charge. If a neutral atom gains one or more electrons it becomes an anion. Cl 17 protons 17 electrons Cl - 17 protons 18 electrons

Atomic Radii Li Na K Rb Cs Cl S P Si Al Br Se As Ge Ga I Te SbSn In Tl Pb Bi Mg Ca Sr Ba Be F O N C B IA IIA IIIA IVA VA VIA VIIA = 1 Angstrom IA IIA IIIA IVA VA VIA VIIA = 1 Angstrom Li 1+ Be 2+ Na 1+ Mg 2+ Ba 2+ Sr 2+ Ca 2+ K 1+ Rb 1+ Cs 1+ Cl 1- N 3- O 2- F 1- S 2- Se 2- Br 1- Te 2- I 1- Al 3+ Ga 3+ In 3+ Tl 3+ Ionic Radii

A monatomic ion contains only one atom  Na +, Cl -, Ca 2+, O 2-, Al 3+, N 3- A polyatomic ion contains more than one atom  OH -, CN -, NH 4+, NO 3-

Oxidation State of Elements Se 2- Te Al 3+ Zn 2+ Ag 1+ N 3- O 2- F 1- Cl 1- S 2- Br 1- I 1- Period Be 2+ Na + K+K+ Rb + Cs + Ba 2+ H+H+ Li + Ca 2+ Sr 2+ Mg 2+ Group NOBLEGASESNOBLEGASES Transition metals

A MOLECULE is 2 more atoms bonded together – they may be the same element (ie diatomic molecule) or they may be different elements (ie caffeine) Composition of molecules is given by a MOLECULAR FORMULA H2OH2OH2OH2O C 8 H 10 N 4 O 2 - caffeine

Compounds composed of 2 or more elements in a fixed ratio properties differ from those of individual elements EX: table salt (NaCl)

Ionic Compound ionic compounds consist of a cation and an anion. The sum of the charges on the cation and anion in each compound must equal zero. The ionic compound NaCl

How to Combine Ions Na +1 Cl -1 Mg +2 Al +3 NaCl The charges need to equal zero in a compound. +1-1=0 Mg 3 Al =0 3 Mg atoms are needed and 2 Al atoms are needed to get the overall charge to equal zero. The charges need to equal zero. You may have more than one atom of each element to get the total charge of the compound to equal zero.

Naming Cations NAMING: The atomic cations are named just like the neutral element followed by the word ion: For example: K + is the potassium ion MULTIPLE IONS: To distinguish the atomic ions Fe 3+ from Fe 2+ we name them iron(III) ion and iron(II) ion

Naming Anions The simplest negative ions, consisting of a single atom of a given element. Use the root of the element’s name and add -ide to get the name of the most common anion. Examples are:  (1 st row): H - is the hydride ion  (2 nd row): N 3- is the nitride ion ; O 2- is the oxide ion ; F - is the fluoride ion  (3 rd row): P 3- is the phosphide ion; S 2- is the sulfide ion; Cl - is the chloride ion

Polyatomic Ions You must memorize the names of common polyatomic ions

Isotopes Atoms of the same element (same Z) but different mass number (A). Boron-10 ( 10 B) has 5 p and 5 n Boron-11 ( 11 B) has 5 p and 6 n 10 B 11 B

Isotopes & Their Uses Bone scans with radioactive technetium-99.

Isotopes Isotopes are atoms of the same element having different masses due to varying numbers of neutrons. IsotopeProtonsElectronsNeutronsNucleus Hydrogen–1 (protium) 110 Hydrogen-2 (deuterium) 111 Hydrogen-3 (tritium) 112

Lithium has an atomic mass of 6 and an atomic number of 3. This isotope of Lithium has 3 neutrons.

Atomic Symbols Show the name of the element, a hyphen, and the mass number in hyphen notation sodium-23 Show the mass number and atomic number in nuclear symbol form mass number 23 Na atomic number 11

Isotopes? Which of the following represent isotopes of the same element? Which element is it? 234 X 234 X 235 X 238 X

CARBON-14 – RADIOACTIVE ISOTOPE Occurs in trace amounts in the atmosphere Absorbed into living organisms The half-life of carbon- 14 is approx 5700 years (when half the C-14 is converted to N-14)

All green plants maintain a constant level of carbon 14 while alive. Once the plant dies, the carbon 14 starts to deteriorate at a precise rate that is well documented and measurable, via the use of calibration curves. Using the remaining carbon 14 the date that the plant died can be worked out. The date is not totally precise and can vary up to at least fifty years of the year obtained from the results.