Elements and The Periodic Table 1 Element squares

Elements and The Periodic Table 1) Element squares 2) Atomic Number 3) Atomic Mass 4) Valence Electrons 5) Metals/Non-Metals and Metalloids 6) Groups and Families 7) Periods

The Elements • There are 118 elements – 98 of which occur naturally • The remainding 20 have been created in the lab • The universe as we know it is created out of these elements

The Elements and Atoms • Element – matter that is composed of one type of atom – Elements are abbreviated in scientific shorthand – either a letter or a pair of letters called chemical symbol. – Ex: Aluminum – Al Copper – Cu • Atom – smallest part of an element that still has the properties of the element

Atoms • Atoms have 2 regions 1) Nucleus: the center of the atom that contains most of the mass of the atom. 2) Electron cloud: surrounds the nucleus & takes up most of the space of the atom

Atoms • In the nucleus we find: – Protons: positively (+) charged subatomic particles – Neutrons: neutrally charged subatomic particles • In the electron cloud we find: – Electrons: the subatomic particle with a negative (-) charge and relatively no mass

Atomic Number and Atomic Mass • Atomic number = number of protons in an atom – Ex: Hydrogen’s atomic number is 1 • hydrogen has 1 proton – Ex: Carbon’s atomic number is 6 • carbon has 6 protons **The number of protons identifies the atom it’s an atom’s fingerprint.

How do we know the number of neutrons in an atom? • Atomic Mass: the number of protons plus neutrons in the nucleus • number of neutrons = atomic mass - atomic number Example – Li has a atomic mass of 7 and an atomic number of 3 • Protons = 3 (same as atomic number) • Neutrons= 7 -3 = 4 (atomic mass - atomic number)

How do we find the number of electrons in an atom? • Most atoms are neutral (have no overall charge) • Because the only charged subatomic particles are the protons and electrons… they must balance each other out in an electrically neutral atom. • Therefore. . – Number of Electrons = number of Protons in a neutral atom. – If the number of protons is 8 (+) then the number of electrons is 8 (-)

Why is the Periodic Table Important? • The periodic table organizes all the known information about the elements

The Current Periodic Table • The periodic table arranges the elements by atomic number • The horizontal rows are called periods and are labeled from 1 to 7 • The vertical columns are called groups are labeled from 1 to 18

How are protons, neutron and electrons arranged in an atom?

The Periodic Table • The periodic table organizes the elements in a particular way. • HOW? ? ? • By the atomic number

Atomic Numbers Elements are organized on the table according to their atomic number, usually found near the top of the square.

What does each square tell us? Different periodic tables can include various bits of information, but usually include the – atomic number – symbol – atomic mass – state of matter at room temperature

Atomic Number • Refers to how many protons an atom of that element has • No two elements have the same number of protons

Atomic Mass • Atomic Mass refers to the “weight” of the atom • It is found by adding the number of protons and the number of neutrons

Valence Electrons • Valence electrons are the electrons in the outer energy level of an atom

Metals, Non-Metals, and Metalloids Use the handout to colour your top periodic table like this. Make sure you include a legend

Properties of Metals • Metals are good conductors of heat and electricity • Metals are shiny • Metals are ductile (can be stretched into thin wires) • Metals are malleable (can be pounded into thin sheets) • A chemical property of metal is its reaction with water, which results in corrosion

Properties of Non-Metals • Non-metals are poor conductors of heat and electricity • Non-metals are not ductile or malleable • Solid non-metals break easily. • They are dull • Many non-metals are gases

Properties of Metalloids • Metalloids (metal-like) have properties of both metals and non-metals. • They are solids that can be shiny or dull. • They conduct heat and electricity better than nonmetals but not as well as metals. • They are ductile and malleable. Silicon is used in many computer chips

Columns and Families • Elements in the periodic table are group into 18 columns • Each element within a column or group contains the same number of valence electrons – This results in them having similar properties

Columns and Families • Some of these columns are further divided into special families • Elements in each family have similar but not identical properties. • For example, lithium (Li), sodium (Na), potassium (K), and other members of family IA are all soft, white, shiny metals.

Hydrogen • The hydrogen square sits atop Group 1, but it is not a member of that family. Hydrogen is in a class of its own. • It’s a gas at room temperature. • It has one proton and one electron in its one and only energy level. • Hydrogen only needs 2 electrons to fill up its valence shell. Assign Hydrogen a colour and use the second periodic table to colour it in. **Include it on your legend**

Alkali Metals • The alkali family is found in the first column of the periodic table. • Atoms of the alkali metals have a single electron in their outermost level • They are shiny, soft and have the consistency of clay • They react violently with water and so are never found free in nature. Sodium metal Assign alkali metals a colour and use the second periodic table to colour it in. **Include it on your legend**

Alkaline Earth Metals • They are very reactive but not as reactive as group 1 • They have two valence electrons. • Alkaline earth metals include magnesium and calcium, among others. Assign alkali metals a colour and use the second periodic table to colour it in. **Include it on your legend** Magnesium metal strip

Transition Metals • These are the metals you are most familiar with: copper, tin, zinc, iron, nickel, gold, and silver • For many, their number of valence electrons is variable (changes) • They are good conductors of heat and electricity Assign transition metals a colour and use the second periodic table to colour it in. **Include it on your legend**

Halogen Family • The elements in this family are fluorine, chlorine, bromine, iodine, and astatine • Halogens have 7 valence electrons, and are very reactive, therefore, they are never found free in nature Assign halogens a colour and use the second periodic table to colour it in. **Include it on your legend** Chlorine gas (Cl 2) contains two chlorine atoms bonded together and is poisonous

Nobel Gases • Noble Gases are colorless gases that are extremely unreactive • They are inactive because their outermost energy level is full • The family of noble gases includes helium, neon, argon, krypton, xenon, and radon. • All the noble gases are found in small amounts in the earth's atmosphere. Assign nobel gases a colour and use the second periodic table to colour it in. **Include it on your legend** Helium is lighter than air. This allows balloons filled with it to float.

Rare Earth Elements • The thirty rare earth elements are composed of the lanthanide and actinide series • Most are synthetic or man-made • Look at your periodic table and determine where they should be Assign rare earth elements a colour and use the second periodic table to colour it in. **Include it on your legend**

Rows and Periods • Elements in the periodic table are also grouped into rows or periods – The periods are numbered 1 -7 • Elements within a period do not share common characteristics – This is because they each have a different number of valence electrons

Examples • He has a mass # of 4 and an atomic # of 2 – p+ = 2 no = 2 e- = 2 • Cl has a mass # of 35 and an atomic # of 17 – p+ = 17, no = 18, e- = 17