What are atoms and how are they structured? Bell Work Thursday- 9/3 What are atoms and how are they structured?

Basic Chemistry Chapter 6 Section 1 5th century BC- Leucippus and Democritus first proposed the idea that all matter us made up of tiny, indivisible particles 1800s- scientists began to collect evidence supporting the existence of atoms As technology improved, we were able to see that atoms are made up of even smaller particles

Atoms Atoms are the building blocks of matter Three basic sub-atomic particles PROTONS: positively charge; located in the nucleus NEUTRONS: neutral; located in the nucleus ELECTRONS: negatively charged; located outside nucleus

Atoms cont. Atomic structure is a result of the attraction between protons and electrons

Atomic Structure Protons and neutrons are contained inside the nucleus Protons are represented by atomic number Number of neutrons can be predicted by subtracting the atomic mass from the atomic number and rounding to the nearest whole. Number of electrons in a neutral atom should equal the number of protons

Oxygen Draw electronic configuration Remember energy levels 1st- 2 electrons 2nd- 8 electrons 3rd- 8 electrons

Oxygen Second energy level Protons (+ charge) Nucleus First energy level Electrons Neutrons (no charge)

Elements Pure substances that cannot be broken down into other substances Organized by characteristics on the Periodic Table

Periodic Table Vertical- Groups Horizontal- Periods

Isotopes Proton number (atomic number) is equal to the number of electrons, but NEUTRON number can vary. Atoms of the same element with different neutron numbers are called isotopes. Changing neutron number can make the atom unstable and cause it to decay. When this happens, the isotope gives off radiation

Radioactive Isotopes Changing the number of neutrons can affect the stability of the nucleus When a nucleus breaks apart, it gives off radiation Carbon-14 is a radioactive isotope found in all living things Calculate age of object by measuring half life Scientists know the amount of time it takes for half of Carbon-14 to decay Calculate age by finding out how much Carbon-14 remains Medical uses- other radioactive isotopes can be injected into a patient to diagnose disease and locate certain types of cancer Cancer cells have a higher metabolic rate and therefore uptake the radioactive isotopes faster so you can see it in a scan

Compounds A substance formed from two or more elements bonded in a specific ratio Ex: CO2, NAOH, H2O, H2O2 Cannot be broken down into smaller parts physically; i.e. cannot be individually crushed or torn Can be broken down chemically Examples: Salt (NaCl), Water (H2O), Methane (CH4)

How many protons, neutrons, and electrons does Sulfur have? Bell work 9/4 How many protons, neutrons, and electrons does Sulfur have? Especially this Friday because FSU football starts TOMORROW!!!

Electronic configuration

Atomic Structure and Octet Rule Electrons travel outside the nucleus in energy levels The first level holds up to two electrons The second holds up to 8 electrons The third holds up to 8 Full energy levels are more stable than partially filled ones Bonds are formed between atoms with unfilled energy levels because unstable atoms tend to bond

Chemical Bonds Ionic Covalent A bond formed when one atom donates one or more electrons to another atom. Both atoms become charged and are called “ions” The electrical charges of the atoms attract them to each other A bond where a molecule is formed by two or more atoms SHARING electrons Covalent bonds can be single, double, or triple bond depending on how many electrons are shared

Covalent Bonds Two atoms will share one, two, or three electrons. The electrons travel between the electrons shells of both atoms. Ex: H2O H2 O2 These electrons are shared

Covalent bond

Ionic Bonds The atom with fewer electrons will donate to the atom with more electrons. The atom that receives the electrons becomes negatively charged The atom that donates the electrons becomes positively charged The two atoms are attracted to each other, like magnets Ex: Na+ Cl-

Van der Waals Forces Electrons travel around the nucleus inconsistently. This leads to temporary positive or negative areas. When molecules come close together, these temporary positive and negative areas are attracted to each other This causes molecules to be attracted to each other. This attraction is known as van der Waals forces. In water, this causes cohesion, which is the reason water beads together.

Carbon

Carbon

Aluminum

Aluminum

Potassium

Potassium

Potassium

Bonding Use electron configuration to explain why Hydrogen and Oxygen bond together.

Covalent Bond

Bonding Use electron configuration to explain why Sodium and Chlorine bond together.

Ionic Bond