Unit 2 Flashcards
What are Elements? Explain them.
Elements are pure substances from which all other things are built.
- They cannot be broken down into simpler substances.
- They can join with other elements to form compounds.
What are Chemical Symbols?
Chemical Symbols represent the names of the elements. They consist of one or two letters.
Ex: C -> Carbon
Ex: Al -> Aluminum
Explain the Periodic Table.
- The periodic table organizes elements. Elements are arranged according to properties
- Groups (or families) contain elements with similar properties in vertical columns.
- Periods are horizontal rows of elements, counted from top to bottom.
How many periods and groups (families) are there?
There are 7 Periods and 18 groups
Explain group numbers.
Group numbers are written at the top of each vertical column.
- The letter A is for representative elements (1A-8A)
- The letter B is for transition elements (3B-12B)
An alternative system uses numbers 1-18 for all the groups.
Where are Alkali Metals located?
Group 1
- Alkali Metals are very reactive
Where are Alkaline Earth Metals located?
Group 2
- Not as reactive as group 1 metals
Where are Transition Metals located?
Group 3-12
Where are Halogens located?
Group 17
- They are highly reactive and form compounds with most elements
Where are Noble Gases located?
Group 18
Explain Metals
All metals Except hydrogen are located on the left of the periodic table.
- They are shiny and ductile, and conduct heat and electricity.
- They are solid, except for mercury (Hg).
Explain Nonmetals
Located on the right side of the periodic table including hydrogen.
- They are dull, brittle, and poor conductors but often good insulators.
- They have low densities and melting points.
Explain Metalloids
Located along the heavy zigzag line on the periodic table.
- Exhibit properties of metals and nonmetals
- Are better conductors than nonmetals but not as good as metals.
What are the 4 elements that make up the majority of our body mass?
Oxygen, Carbon, Hydrogen, Nitrogen
- Makes up 96% of our body mass
What are Macrominerals?
Elements that are essential to our health.
What is an Atom?
An atom is the smallest particle of an element that retains the characteristics of that element.
What is the Dalton Atomic Theory?
Atoms…
- are tiny particles of matter of an element
- are similar to each other and different from those of other elements
- of two or more different elements combine to form compounds
- are rearranged to form new combinations in a chemical reaction
!! Atoms are never created or destroyed during a chemical reaction!!
What makes up an Atom? Explain
Protons: have a positive charge
Electrons: have a negative charge
Neutrons: have no charge
- Like charges repel and unlike charges attract
Where is the Nucleus located? What does it contain?
A nucleus is located in the center of the atom, which contains protons and neutrons.
Explain the Mass of the Atom.
In an atom, the protons and neutrons that makeup almost all the mass are packed into the tiny volume of the nucleus. The electrons surround the nucleus and account for the large volume of the atom.
What is the Atomic Mass Unit (amu)?
Because the mass of subatomic particles is so small, chemists use a very small unit of mass called the atomic mass unit (amu)
- 1 amu = 1 Dalton
- !!Electrons have such a small mass that they are not usually included in the mass of an atom!!
What is the symbol, charge, mass, and location of a Proton?
Symbol: p+
Charge: +1
Mass (amu): 1.007
Location in Atom: Nucleus
What is the symbol, charge, mass, and location of a Neutron?
Symbol: n
Charge: 0
Mass (amu): 1.008
Location in Atom: Nucleus
What is the symbol, charge, mass, and location of a Electron?
Symbol: e-
Charge: -1
Mass (amu): 0.00055
Location in Atom: Outside the Nucleus
Explain the Atomic Number
- A whole number specific for each element
- Its equal to the number of protons in an atom
What if a carbon atom has 3 protons instead of 6 protons?
Then it wouldn’t be a carbon atom, it would be lithium.
Explain neutral atoms.
The net charge is zero.
number of protons=number of electrons
Explain the mass number
The mass number is not listed on the periodic table.
- It represents the number of particles
- It is equal to the number of protons + the number of neutrons.
How do you get the number of protons?
The atomic number = the number of protons
How do you get the mass number?
The number of protons + neutrons = mass number
How do you get the number of neutrons?
The mass number- the atomic number = the number of neutrons
What are Isotopes?
Isotopes are atoms of the same element that have different mass numbers.
- They have the same number of protons but different numbers of neutrons.
Explain Electromagnetic Radiation.
Electromagnetic radiation consists of energy particles that move as waves of energy.
- We experience electromagnetic radiation in different forms, such as light, colors, or x-rays
What is a wavelength, peak, and trough? Explain them
- The distance between peak to peak or trough to trough is a wavelength.
- A peak is the highest part
- A trough is the lowest part
High-energy radiation has shorter wavelengths.
Low-energy radiation has longer wavelengths.
What is the Atomic Spectrum?
When light from a heated element passes through a prism, it separates into distinct lines of color separated by dark areas called an atomic spectrum. Each element has its own unique atomic spectrum.
Explain Electron Energy Levels.
The lines in an atomic spectrum are associated with changes in the energies of the electrons. In an atom, each electron has a specific energy known as its energy level.
What are Principle Quantum Numbers?
Each electron energy level is assigned principal quantum numbers (n). It increases in energy as the value of n increases and electrons are further away from the nucleus.
- The energy level is quantized (electrons can have only specific energy values)
True or False: Electrons with the same energy are grouped in the same energy level.
True: Energy levels are assigned values called principle quantum numbers
Explain changes in electron energy levels.
Electrons move to a higher energy level when they absorb energy. When electrons fall back to a lower energy level, light is emitted.
- The energy emitted or absorbed is equal to the differences between the two energy levels.
Explain sublevels.
It is the arrangement of electrons that determines the physical and chemical properties of an element.
- Each energy level consists of one or more sublevels.
- The number of sublevels in an energy level is equal to the principal quantum number n of that energy level.
- The sublevels are identified as s, p, d, and f
Explain s Orbitals.
The electron cloud of an s orbital represents the highest probability of finding an s electron.
The s orbital are shown as spheres. The sizes of the orbital increases because they contain electrons at higher energy levels.
Explain p Orbitals.
There are three p orbitals. Each orbital is aligned along a different axis from the other p orbital.
All three p orbitals are dumbbell shaped and are shown around the nucleus.
Explain d Orbitals.
The d sublevel contains 5 d orbitals.
Four of the five orbitals consist of four lobes that are aligned along or between different axes. One d orbital consist of two lobes and a doughnut shaped ring around its center.
Explain the Pauli exclusion principle.
It states that…
- each orbital can hold a maximum of two electrons
- electrons in the same orbital repel each other
- electrons in the same orbital must have their magnetic spins cancel (they must spin in opposite directions) We can represent this with arrows
How many orbitals and electrons does sublevel s can hold?
Each s sublevel has 1 orbital and can hold a maximum of 2 electrons.
How many orbitals and electrons does sublevel p can hold?
Each p sublevel has 3 orbitals and can hold a maximum of 6 electrons.
How many orbitals and electrons does sublevel d can hold?
Each d sublevel has 5 orbitals and can hold a maximum of 10 electrons
How many orbitals and electrons does sublevel f can hold?
Each f sublevel has 7 orbitals and can hold a maximum of 14 electrons.
Explain Orbital Diagrams.
Orbital diagrams use boxes to show how electrons are arranged in the orbital of an atom .
Explain Electron Configurations.
Electron configuration is a notation that indicates the placement of electrons in an atom.
- write an abbreviated form using a noble gas to represent all electrons preceding it.
Where is the s block on the periodic table?
Where is the p block on the periodic table?
Where is the d block on the periodic table?
Where is the f block on the periodic table?
What are Valence electrons?
They are electrons in the outermost energy level.
For representative elements in groups 1A-8A, chemical properties are mostly due to valence electrons. (The group number gives the number of valence electrons for the representative elements)
What are Lewis symbols?
Lewis symbols represent the valence electrons as dots placed on the sides of the symbol for an element.
Explain Atomic Size.
It is determined by the atom’s atomic radius, the distance between the nucleus and the outermost electrons.
- For representative elements, the atomic size increases going down a group but decreases going from left to right across a period.
What is Ionization Energy?
It is the energy required to remove one of the outermost electrons (valence electron).
- Ionization energy decreases down a group and increases going across a period from left to right.
Explain Metallic Character.
An element with a metallic character is one that loses valence electrons easily.
- The metallic character of the representative elements increases going down a group and decreases going from left to right across a period.
Do you understand this?
Yes
Explain Ionic bonds.
Ionic bonds occur when valence electrons of a metal atom are transferred to the atom of a nonmetal.
Explain Covalent bonds.
Covalent bonds occur when nonmetal atoms share electrons to attain a noble gas arrangement.
Name this polyatomic ion: OH-
Hydroxide
Name this polyatomic ion: NH4+
Ammonium
Name this polyatomic ion: NO3-
Nitrate
Name this polyatomic ion: ClO4-
Perchlorate
Name this polyatomic ion: CO3^2-
Carbonate
Name this polyatomic ion: HCO3-
Hydrogen carbonate (bicarbonate)
Name this polyatomic ion: CN-
Cyanide
Name this polyatomic ion: C2H3O2-
Acetate
Name this polyatomic ion: SO4^2-
Sulfate
Name this polyatomic ion: HSO4-
Hydrogen sulfate (bisulfate)
Name this polyatomic ion: PO4^3-
Phosphate
Name this polyatomic ion: HPO4^2-
Hydrogen phosphate
Explain how to name a Molecular Compound.
- the first nonmetal in the formula is named by its element name
- the second nonmetal is named using the first syllable of the name followed by ide
Example CO2 is carbon dioxide
Explain the molecule H2
Its the simplest molecule
- It forms as the atoms move closer and the positive charge of the nucleus attracts the electron or the other atom
What is a Lewis Structure?
A molecule is represented by a Lewis structure in which the valence electrons of all the atoms are arranged to give octets.
What is electronegativity?
Its the ability to attract the shared electrons in a chemical bond.
- It increases from left to right going across a period
- It decreases going down a group
- Its high for nonmetals and low for metals
Explain nonpolar covalent bonds.
A nonpolar covalent bond occurs between nonmetals.
- It is an equal or almost equal sharing of electrons by the two bonding atoms (between 0.0-0.4)
Explain polar covalent bonds.
A polar covalent bond occurs between nonmetal atoms
- It is an unequal sharing of electrons (from 0.5-1.8)
What is a DIpole?
A polar covalent bond becomes more polar as the difference in electronegativity increases. The separation of charges in a polar bond is called a dipole.
The positive and negative ends of the dipole are located by using the lowercase Greek letter delta with a positive or negative charge and an arrow.
