Science Chapter 11 & 12

If an atom loses an electron, it becomes _______ . If an atom gains an electron, it becomes _________.

"+" charged "-" charged For example, what happens to Cl if it gains an electron? It becomes negatively charged by one electron shown by, Cl-.

Mendeleev saw that when the elements were arranged in order of increasing atomic mass, those that had similar properties occurred in a repeating pattern. That is, the pattern was periodic. Periodic means ____

"happening at regular intervals." The days of the week are periodic. They repeat in the same order every 7 days. Similarly, Mendeleev found that the elements' properties followed a pattern that repeated every seven elements. His table became known as the periodic table of the elements.

The Atomic Mass (AMU) =

# of protons + # of neutrons

An atom that has 117 protons in its nucleus has not yet been made. Once this atom is made, to which group will element 117 belong? Explain your answer.

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Are the properties of sodium, Na, more like the properties of lithium, Li, or magnesium, Mg? Explain your answer.

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The metal thallium occurs naturally as 30% thallium-203 and 70% thallium-205. Calculate the atomic mass of thallium.

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Each proton and neutron has a mass of _____ Atomic Mass Unit (amu) and is located in the ______.

1 Nucleus

Niels Bohr - 1913

1) Bohr received his doctorate in physics from the University of Copenhagen in 1911 2) In 1913, Bohr published a theory about the structure of the atom based on an earlier theory of Rutherford's. 3) Bohr expanded upon this theory by proposing that electrons travel only in certain successively larger orbits. He suggested that the outer orbits could hold more electrons than the inner ones, and that these outer orbits determine the atom's chemical properties. 4) Mid - 1900's scientist that hypothesized that electrons are distinct in orbits

The History of the Atomic Model

1) Dalton's atom 2) Thompson's plum-pudding atom 3) Rutherford's atom 4) Bohr's planetary atom 5) Current Orbital atom

History of the Atomic Model

1) Dalton's atom - 1803 2) Thompson's plum-pudding atom - 1904 (positive and negative charges) 3) Rutherford's atom - 1911 ( The nucleus) 4) Bohr's planetary atom - 1913 (Energy levels) 5) Current Orbital atom - 1926 (Electron Cloud)

J.J. Thompson - 1897 British Scientist - late 1800's scientist found the electron and other smaller particles.

1) Discovered that the atom has smaller particles inside it 2) Used his cathode-ray tube and discovered negatively charged "corpuscles" now known as the electron 3)His discovery lead to a revised model of the atom called the "plum pudding model"

Ernest Rutherford - 1909 Did gold foil experiment which proved, in early 20th century, that atoms had a nucleus.

1) Experimented to test Thompson's theory 2) Experimented by sending positively charged particles at gold foil that was surrounded by zinc sulfide and the zinc sulfide would glow if struck by the particles. 3) He thought the particles would go through the gold but instead the particles were deflected 4) From his results a new model of the atom was developed that included a positive nucleus surrounded by electrons moving around it 5) Discovered the positive nucleus

Who was Democritus?

1) Greek Philosopher of 440 BC 2) Believed all matter existed as pieces called "atomos" or atoms 3) "Atomos" means indivisible or uncuttable 4) He believed all atoms were small, hard pieces made of one type of material and these were always moving

So if we have a Li atom that has 3 protons and 3 neutrons, what is the atomic mass?

3p + 3n = 6 amu

What is an element?

A pure substance that cannot be separated or broken down into simpler substances by physical means.

What is an atom?

A single part of an element The smallest particle into which an element can be divided and still be the same substance.

What is a theory?

A unifying explanation for a broad range of hypotheses and observations that have been supported by testing.

IMPORTANT TO REMEMBER: The number of protons _________

ALWAYS determines the element

The definition of an ion is

An atom or molecule that has gained or lost one or more e- and thus has become electrically charged.

How does an atom become a positively-charged ion?

An atom that loses one or more electrons becomes a positively-charged ion. An atom that gains one or more electrons becomes a negatively-charged ion.

Aristotle, Greece, 400 BC

Aristotle did not believe in Democritus' atom. He believed that all matter was made of fire, earth, air, & water. Like Democritus, he did no scientific experimentation to support his theory.

Quick formulas to remember for finding atomic mass and electric charge...

Atomic Mass = #protons + #neutrons Atomic Charge = Protons - Electrons The number of protons can always be found by looking up the atomic number of the Periodic Table.

It is the _________ that identifies an element. If an element has 1 proton, then it will always be _______. If an element has 20 protons, then it will always be __________. If an element has 104 protons, then it will always be ____________.

Atomic Number Hydrogen Calcium Rutherfordium

All atoms of an element has the same _______

Atomic number Example: All Carbon atoms have 6 protons and therefore an atomic number of 6. All silver atoms have 47 protons and therefore an atomic number of 47.

How can you tell one isotope from another?

By the mass number. Mass Number = # of protons + # of Neutrons in an atom

Looking at the picture. The protons and neutrons are in the _________ of the atom. Scientist call the center of the atom the _______.

Center Nucleus

Refer back to the picture - Notice the charge "+" "-" or "0" is the symbol that refers to Charge The _______ always has negative charge, shown by e- The ________ always has a positive charge, shown by p+ The _________ has no charge or neutral and is represented by n0.

Electron Proton Neutron

The ______are always found whizzing around the nucleus in ________. (Also called energy levels or electron shells

Electrons Orbital Shells.

The number of protons always determines the _____.

Element

Why is a group sometimes called a family?

Elements in the same group often have similar chemical and physical properties.

What are the four basic forces within an atom?

Gravitational Force - pulls objects Electromagnetic force - same charge repel, opposite charge pulls toward each other Strong force - Push away from each other due to electromagnetic force. weak force - important in radioactive atoms. EX: A neutron can change into a proton or an electron

Why is gravitational force in the nucleus so small?

Gravitational forces are within the atom. Because the atom is so small, the gravitational force is small.

Some examples of elements are:

Hydrogen Carbon Oxygen Zinc Argon

Compare a period and a group on the periodic table.

In a period, the physical and chemical properties of elements in a row follow a repeating pattern. In a group often has similar chemical and physical properties.

Please keep these important rules in mind... If the charge of an entire atom is zero (or neutral), this means there are equal numbers + and - particles (or protons and electrons). If you have more electrons than protons, the atom has a net negative charge. If you have more protons than electrons, the atom has a net positive charge. An atom with a charge (either positive or negative) is called an ______.

Ion ( "+" ion = cation and "-" ion = anion)

An atom that has the same number of protons (or the same atomic number) as other atoms of the same element do but that has a different number of neutrons (and thus a different atomic mass)

Isotope

These atoms are called _________, which means two or more atoms that have the same number of protons but different numbers of neutrons.

Isotopes

The Periodic Table was designed by _________ , as a way of organizing the elements.

Mendeleev in 1869

Could atoms of the same element have different number of protons?

NEVER!! It is not possible for atoms of the same element to have differing numbers of protons. Protons determine the identity of the atom. For example, if we have an atom that has 3 protons and 3 neutrons, it is Lithium with an atomic mass of 6 amu. If we have an atom that has 3 protons and 4 neutrons it is Li with an atomic mass of 7

How many electrons and protons are in the following ions?

Na+ removes an electron making it a positive ion F- removes a proton making it a negative ion O-2 removes two protons making it a negative ion

Each electron has a ______ charge and an amu of _______. Also located in the ________.

Negative & 0 Electron Cloud

Where are electrons in an atom?

Negative charged outside of the nucleus in an atom.

Where are neutrons in the atom?

Neutral charge inside the nucleus of an atom.

Could a nucleus of more than one proton but no neutrons exist? Explain.

No because you could not build a nucleus, because the protons are the same charge and would repel each other.

Non metals are _____

Not malleable Not conductors Not shiny Not good conductors of Thermal Energy (Heat)

Each horizontal row of elements (from left to right) on the periodic table is called a

Period. The physical and chemical properties of elements in a row follow a repeating, or periodic, pattern as you move across the period.

All elements are organized on the ______.

Periodic Table

There are more than 110 different elements. Which are all organized on the _________.

Periodic Table

Name the two kinds of particles that can be found in the nucleus.

Proton Neutron

Each element contains an exact amount of _________. This is known as the ___________.

Protons Atomic Number

Keep the following rule in mind: The number of _______ determines the identity of the element and the number of __________ determine the particular isotope.

Protons Neutrons Examples: 1. An atom of sodium has an atomic number of 11 which means it has 11 protons. If this sodium has an atomic mass of 23, how many neutrons does it contain? #protons + #neutrons = amu (the atomic mass equation) 1. 11 + #neutrons = 23 2. #neutrons = 23 - 11 3. #neutrons = 12

There are three main parts of the atom:

Protons Neutrons Electrons

Each element contains an exact amount of _______. This is known as the ______.

Protons atomic number

Atomic Mass and Charge: As you can see from the picture, ________ and ________ are bigger than electrons. Thus, the atomic mass or weight of an atom is determined by adding the number of protons and neutrons together

Protons & Neutrons

Modern Atomic Theory: Many scientist have contributed to our current understanding of the atom including Schrodinger, Heisenberg, Chadwick, et al. What do we now believe is located in the nucleus of an atom?

Protons and Neutrons

What are the charges for Protons?

Protons are positively charged subatomic particles in the nucleus.

Demitri Mendeleev - 1863

Russian Chemist Began classifying elements and noticed patterns existed in their properties Organized the first Periodic Table

What are four properties shared by most metals?

Shiny Good Conductors of electric current Malleable (can be flatten by a hammer and will not shatter Good conductors of Thermal Energy (Heat)

In the model of the copper atom above: 2. How many protons and neutrons are found in a copper atom that has an atomic mass of 65?

Solution: From the periodic chart, we see copper is element 29. So, we know immediately that copper has 29 protons. Then using the equation below: #protons + #neutrons = amu (the atomic mass equation) 1. 29 + #neutrons = 65 2. #neutrons = 65 - 29 3. #neutrons = 36

John Dalton - 1803 British Chemist and School Teacher Developed his Atomic Theory or Particle Theory

States: 1) All substances are made of atoms 2) Atoms are small particles that can't be broken into smaller pieces - Like a marble and can't be created or destroyed or divided 3) Atoms of the same element are exactly alike in characteristics and properties 4) Atoms of different elements combine to form compounds 5) Worked with gases in 1808 and published theory that atoms were hard spheres

The charges of protons and electrons are opposite but equal, so their charges cancel out. Because an atom has no overall charge, it is neutral. What happens if the numbers of electrons and protons are not equal?

The atom becomes a charged particle called an ion

What has to happen to an atom in order for it to become charged?

The atom must gain or lose an electron, e- An atom can't lose a proton, p+, because this determines its elemental identity.

Why are alkali metals more reactive than transition metals are?

The atoms of transition metals do not give away their electrons as easily as atoms of the Group 1 and Group 2 metals do.

Some atoms of boron have a mass # of 10 and some have a mass # of 11.

The atoms would be called Boron-10 and Boron-11.

What are the charges for electrons

The charge is negatively charged subatomic particles in the electron cloud

What are the charges for Neutrons?

The charge is neutral (no charge) subatomic particles in the nucleus.

Electrons are located in electron shells or electron energy levels around the nucleus. Scientists have named these shells k, l, m, n, o, p, and q as follows:

The k-shell only holds 2 electrons The l-shell only holds 8 electrons The m-shell only holds 18 electrons (8) The n-shell only holds 32 electrons (8)

Protons and Atomic Number: How can you tell which elements these atoms represent?

The key is the number of protons. The number of protons in the nucleus of an atom is the atomic number of that atom.

The Atomic number =

The number of protons

Properties of Transition Metals:

The properties of the transition metals vary widely. these elements are metals, they share the properties of metals. Transition metals tend to be shiny and to conduct thermal energy and electric current well.

How small is an atom?

There are 100 trillion atoms in an ordinary human cell! An average - sized atom has a diameter of about 0.00000003 cm; three hundred-millionths of a centimeter.

According to the Modern Atomic Theory, how do electrons move around the nucleus?

They whiz around in indefinite patterns and cannot be predicted.

Atom of the same element can have different masses. How can this happen?

This happens when atoms have the same number of protons but different number of neutrons.

Each vertical column of elements (from top to bottom) on the periodic table is called

a group. Elements in the same group often have similar chemical and physical properties. For this reason, a group is also called a family.

Atomic Mass Unit

a unit of mass that describes the mass of an atom or molecule. Ex: A proton has 1 amu (atomic mass unit)

Each Element Is Identified by a Chemical Symbol Each square on the periodic table includes _______

an element's name, chemical symbol, atomic number, atomic mass.

An _____ is a single part of an element.

atom

An atom's _______ is equal to the weighted average of the masses of all the naturally occurring isotopes of that element.

atomic mass

An atom's _______ is equal to the number of protons in its nucleus.

atomic number

Which of the following particles has no electric charge? a. proton b. neutron c. electron d. ion

b. neutron

Dalton developed his atomic theory based on _________.

behaviors of atoms

Which of the following elements should be the best conductor of electric current? S8P1.f a. germanium b. sulfur c. aluminum d. helium

c. aluminum

The valence electrons will become important when we look at _______ Thus, families share similar _______ characteristics.

chemical reactions. Chemical bonding

What property did Mendeleev use to position the elements on the periodic table?

germanium

The Periodic Table is also organized in vertical columns called ______

groups or families.

How had Mendeleev arranged elements when he noticed a pattern?

he arranged the elements in order of increasing atomic mass. When he did so, a pattern appeared.

Elements are arranged _______ and ________in order of ________ and generally increasing ________

left to right top to bottom increasing atomic number atomic mass.

The Periodic Table and Classes of Elements. Elements are classified as ______

metals, nonmetals, and metalloids, according to their properties.

Atoms of most nonmetals have an almost complete set ________.

of electrons in their outer level.

For most elements, the chemical symbol has ______.

one or two letters. The first letter is always capitalized. Any other letter is always lowercase. The newest elements have temporary threeletter symbols.

Where is the proton in an atom?

positive charge inside the nucleus of an atom

The properties of the elements in a group are similar because the atoms of the elements have the same number of electrons in their outer energy level. Atoms will often take, give, or share electrons with other atoms in order to have a complete set of electrons in their outer energy level. Elements whose atoms undergo such processes are called _______

reactive and can combine to form compounds.

An unstable atom is an atom with a nucleus that will change over time. Radioactive atoms _________

spontaneously fall apart after a certain amount of time. As they do, they give off smaller particles, as well as energy.

State the periodic law.

states that the repeating chemical and physical properties of elements change periodically with the elements' atomic numbers.

Metalloids, also called semiconductors, are _________.

the elements that border the zigzag line on the periodic table. Atoms of metalloids have about half of a complete set of electrons in their outer energy level. Metalloids have some properties of metals and some properties of nonmetals

periodic law

the law that states that the repeating chemical and physical properties of elements change periodically with the atomic numbers of the elements

Telling Isotopes Apart You can identify each isotope of an element by its mass number. The mass number is _________.

the sum of the protons and neutrons in an atom. Electrons are not included in an atom's mass number because their mass is so small that they have very little effect on the atom's total mass.

Nonmetals are found where on the periodic table?

to the right of the zigzag line on the periodic table.

All members of families 1, 2, 13, 14, 15, 16, 17, and 18, have the same number of ________, or electrons in their outermost ________.

valence electrons electron shell (Families share the same chemical properties)!

Compared with protons and neutrons, electrons are ____

very small in mass.