Ions, Atoms and Compounds

Chapter 10: Structure, Bonding and Properties

(10.1) Proton Number and the Periodic Table

• Accurate data is close to the true value of measurement.
• Precise data gives similar results upon repetition and are grouped closely together.
• Precision is determined by the smallest division of the measuring instrument.
• In an example, Megan's data was accurate but not precise when measuring aluminum density.
• Bar graphs compare quantities of different categories in a data set.
• In a bar graph, the x-axis represents different categories of data.
• In a bar graph, the y-axis represents the quantities of those categories.
• Line graphs show trends over continuous data.
• In a line graph, the x-axis is the independent variable.
• In a line graph, the y-axis is the dependent variable.
• Atoms comprise all matter and consist of three sub-atomic particles.
• Protons and neutrons reside in the nucleus of an atom and electrons orbit around it.
• Subatomic particle masses are measured in atomic mass units, not grams, due to their light weight.
• Protons and electrons possess an electric charge.

What is Proton Number?

• Proton number refers to the number of protons in the nucleus of an atom of an element.
• The nucleus of an atom consists of positively charged protons and neutrons, which have no charge.
• Every element has a unique proton number.
• Helium has two protons, lithium has three, and gold has 79.
• Proton number is the same as atomic number.
• In the periodic table, elements are arranged by increasing proton number.

What is Nucleon Number?

• Nucleon number, also known as mass number, represents the total count of protons and neutrons within an atom's nucleus.
• In a helium, with 2 protons and 2 neutrons, the nucleon number is 4.
• In a lithium, with 3 protons and 4 neutrons, the nucleon number is 7.
• The formula to calculate nucleon number is: number of protons + number of neutrons.
• The formula to calculate the number of neutrons specifically is: nucleon number - proton number.
• The representation of the Proton and Nucleon Number is as follows
• The nucleon number (mass number), is in superscript to the left of the symbol.
• The proton number (atomic number) is in subscript to the left of the symbol.

Understanding Charge

• Atoms have no overall charge because the number of protons equals the number of electrons.
• The atomic number, representing the proton number, and the mass number, representing the nucleon number, are key identifiers.
• For example, Sodium (Na) with an atomic number of 11 and a mass number of 23 has 11 protons, 11 electrons, and 12 neutrons.
• When there is no overall charge (number of proton = number of electron)
• For example, Lithium (Li) with an proton number of 3 and a nucleon number of 7 has 3 protons, 3 electrons, and 4 neutrons.
• For example, Magnesium (Mg) with an proton number of 12 and a nucleon number of 24 has 12 protons, 12 electrons, and 12 neutrons.
• An atom without a neutron is hydrogen.

Workbook (p.71) Key Points

• In the periodic table, elements are arranged in order of proton number, also known as atomic number.
• A helium atom, composed of 2 protons and 2 neutrons, has a proton number of 2.

(10.2) Electrons in Atoms

• Electrons orbit the nucleus in shells, with the first shell nearest to the nucleus having the lowest energy level.
• The further a shell is from the nucleus, the higher its energy level.
• Each shell can hold a limited number of electrons.
• The first shell holds up to 2 electrons, while the second shell holds 8 electrons.
• Though the third shell can hold 18 electrons, it initially fills up to 8 before the next 2 electrons go into the fourth shell; the remainder then fill the third shell.

Arrangement of Electrons

• The arrangement of electrons is an atom, known as electronic structure or electronic configuration, illustrates electrons orbiting around Magnesium (Mg).
• The magnesium atom, with a proton number of 12, organizes its electrons as follows: 2 in the first shell, 8 in the second shell, and 2 in the third shell, giving it an electronic configuration of 2.8.2 Valence Electrons
• The valence shell, or outer shell, refers to the shell furthest from the nucleus in an atom.
• Valence electrons, also known as outer electrons, are those found within the outer shell of the atom.
• number of electrons in the outer shell identifies the chemical properties.

Patterns in the Electronic Structures

• The number of electrons in the outer shell corresponds to the group number, demonstrating a pattern in the first 18 elements.
• The highest number of electron shells corresponds to the period number.
• The period number of an element reveals the number of occupied electron shells.
• The element’s group number matches the quantity of electrons in its outer shell, specifically for Groups I through VII.
• Elements sharing the same quantity of electrons in their outer shell tend to exhibit similar chemical reactions.

Workbook (p.72) Key Points

• The nucleus in an atom is made up of protons and electrons.

• In a neutral atom, the number of electrons is equal to the number of protons.

• The first electron shell in an atom can hold a maximum of 2 electrons

• The second electron shell in an atom can hold a maximum of 8 electrons.

• The number and arrangement of electrons gives an element its chemical properties.

• Electronic configuration examples

• Helium = 2

• Lithium = 2,1

• Boron = 2,3

• Nitrogen = 2,5

• Fluorine = 2,7

• Magnesium = 2,8,2

• Silicon = 2,8,4

• Sulfur = 2,8,6

(10.3) Making Ions

• The size of atoms increases going down a group.
• Attraction between the nucleus and valence electron becomes less effective when going down a group.
• Going down a group also makes it easier to remove valence electrons and increases reactivity.
• Group VIII is a group of special elements as Noble gases exist, such as helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn).
• Noble gases are monoatomic, exists as single atoms, and are stable, unreactive, while never forming compounds.
• This is because they have a stable or closed electron configuration.
• Helium has two outer electrons in the duplet electronic configuration.
• There are eight outer electrons for noble gases other than helium in the octet electronic configuration.

Understanding Unreactivity and Stability

• Noble gases are unreactive due to their fully occupied outer electron shells, which can be either duplet or octet configurations.
• An atom is stable if it mirrors a noble gas's electronic configuration (duplet/octet).
• Noble gases have a variety of applications from party balloons to shielding gases.
• Noble gases are non-metals, unreactive, and colourless.
• They exist as single atoms.
• Atoms of elements that do not have fully filled outer shells undergo reactions to achieve a stable electron configuration of a noble gas.
• This is achieved by either losing, gaining, or sharing outer electrons, leading to the formation of ions.
• Losing or gaining electrons results in the formation of ions, charged particles within an atom.
• When an atom loses an electron, it forms a cation, which is a positive ion.
• When an atom gains an electron, it forms an anion, which is a negative ion.
• The formulas of ions include Na+, K+, Mg2+, Al3+, NH4‡, Cl-, S2-, O2-, and SO2-.
• Ions form when there's an unequal number of protons and electrons, giving the particle either a positive, or negative charge

Comparing Anions/Cations to a Neutral Atom

When considering a cation

• Number of proton ≠ number of electron.
• There are more protons than electrons in the chemical reaction.
• Example, Na+ has 11 Protons but only 10 electrons.
• It loses 1, 2 or 3 electrons.

When considering an anion

• Number of proton ≠ number of electron.

• There are more electrons than protons in the chemical reaction.

• Example, C1- has 17 protons but only 18 electrons.

• It gains 1, 2 or 3 electrons.

• Atoms bond with each other to obtain a full outer shell of electrons, like the atoms in Group VIII.

• To obtain 8 electrons in their outer shell (or 2, if they have only one shell), atoms will combine with each other to this end.

• Metallic atoms generally only have a few outer electrons.

• To attain the electronic configuration of a noble gas, they tend to lose electrons and form cations.

Lithium

• Lithium is an example of a cation, because the atomic number is 3 and there are only 3 protons.
• lithium can lose one electron to become stable.
• The electronic configuration is then 2,1 which transforms to lithium Li+ with two electrons, and therefore becomes more stable.

Workbook (p.73) Key Points

• An ion is a with a positive or negative charge due to gaining/losing electrons.

• Lithium (Li) = Li+

• Magnesium (Mg) =Mg2+

• Aluminum (Al) = Al3+

• Flouride (F) = F-

• Sulfide (S) = S2-

• Nitride (N) = N3-

• The arrangement of electrons in an atom can be represented using electronic, duplet or octet configuration.

(10.4) Inside Ionic Compounds

• Isotopes are atoms of the same element that contain the same proton number but different numbers of neutrons.

• They contain the same number of protons, same number of electrons and exhibit same proton number.

• They have different nucleon numbers as they exhibit different numbers of neutrons.

• They exhibit the same chemical properties, but differ slightly in their physical properties.

• Same number of protons and electrons in the same element:

• Chemical reactions involve only the electrons, not the neutrons.

• Isotopes have similar chemical properties because of this

• Different number of neutrons within the same element:

• Physical properties are impacted by differences in mass.

• Since isotopes possess differences in mass, they exhibit different physical properties.

Ionic Compounds

• Ionic compounds mostly consist of a metal and a non-metal and forms when metal atoms lose electrons to non-metal atoms.
• When electrons are transferred, this forms positive metal ions and negative non-metal ions, each with full outer electron shells.
• These full shells are called a lattice structure, and the compound has no overall charge.

Ionic Bonding

• In crystal such as salt, millions of sodium ions and chloride ions are held together by electrostatic attraction.
• Called ionic bonding, this works in in all directions, and helps form
• Meaning Lattice refers to the arrangement of cations and anions forming crystal.

Physical properties of Ions

• Lonic bonds are also the forces of attraction that hold the crystal together. Ionic bonds exhibit strong electrostatic forces between the ions.

Formation of Sodium Chloride

• Positive ions are when the sodium has one electron in the outer shell then it loses that same electron making that force for attraction together with electrostatic attraction between Na+ forming to sodium Cl ions.
• Negative ions are when the chlorine atom atoms has seven electrons in its outer shell making Chlorine gains one electron forming that same electron force.

Formation of Magnesium Oxide

• Two is when two electrons is transfers for Mg atoms to O atoms The metal and Non-Metal make that is when magnesium and electrons from magnesium atom to oxygen atom makes. Two electron is transfers on both of this Mg And O the 2 electrons will show what makes a two is the one that is stable because the electrons are transfers makes the atoms to transfers.

Models

• Models helps makes observations to its limitations or helping models
• With strengths for example it shows oppositely the charged ions or shows that is are held together strongly
• It limitation: is does no show for ions which is vibrations on the spote or electrostatic that effects it directions, or Ionic is a brittle.

Metallic bonding

• Metals also have properties with giant ions as well, those ones makes to each to what forms are metallic bonds. and how they connect to the ions that is more easier to attract. or even in the position that is easier for that bond as in a strong position.

Formation of Magnesium Chloride

When Magnesium looses electrons and forms ions magnesium has two or more ions than that also happens from Cl ions.

• Meaning When Mg atoms then goes is makes the bonding in the Cl ions.

(10.7) More About Structures

• Metallic bonds occurs when when something is in a lattice of regular metals these atoms have this bonding on that atom to a lattice.
• A tight packing allows outer electrons to different to there atoms.
• Free in Metals which is Not tired to an ion that make them called is localized.

Physical Properties of Metals

• High melting points- When there is large metal structures this then as well be able to use more energy to its force.
• Malleable and ductility- When materials can be bent and turned to diffrent shaprs.
• Layer Slide can be over each other like as the same metal ions.
• Quick transfers- Its how metal conducts in some metals, they easily can conduct with this said heat transfers.