Chapter 2: The Components of Matter - Elements, Compounds, and Mixtures

These flashcards cover the key concepts from Chapter 2 of the lecture notes focusing on the components of matter including elements, compounds, mixtures, and atomic structure.

What is an element?

A substance that cannot be separated into simpler substances by physical or chemical means.

Simplest type of matter

Made of one type of atom

What is a compound?

A substance composed of two or more elements that are chemically united in fixed proportions (fixed parts by mass).

Properties are diff from elements

How can compounds be separated?

Compounds can be separated into simpler substances by chemical means, but not by physical means.

What is a mixture?

Matter composed of a physical intermingling of two or more substances with a variable composition (components may vary by mass)

Keep properties of elements

What are the two general types of mixtures?

Heterogeneous mixtures and Homogeneous mixtures.

What characterizes a heterogeneous mixture?

A heterogeneous mixture does not possess a uniform composition and different regions may have different concentrations of components.

1+ visible boundaries

What characterizes a homogeneous mixture?

A homogeneous mixture has a uniform composition, such as salt water.

No visible boundaries

What is a solution?

Another term that means a homogeneous mixture; if water is the major component, it is called an aqueous solution.

Who proposed the existence of atoms in the 5th century B.C.?

Democritus.

What does the law of mass conservation state?

The total mass of substances remains constant during a chemical reaction.

Lavoisier made this

What is definite composition?

A chemical compound always contains the same elements in the same parts, or fractions, by mass.

What is the law of multiple proportions?

different compounds that happen to consist of the same element show a mass relationship.

Who proposed Dalton's atomic theory?

John Dalton proposed the atomic theory in the early 1800s.

Atomic theory

1. all matter consist of atoms that cannot be created or destroyed

2. Atoms of one element cannot be converted into atoms of another element. In chemical reactions the original substance separates as atoms, which then combines to form different substances.

3. Atoms of an element are identical in mass and other properties and are different from atoms of any other element

4. Compounds result from the chemical combination of a specific ratio of atoms of different elements

Chemistry

Study of electrons

What do all atoms of an element have in common according to Dalton's theory?

All atoms of an element are identical in mass and other properties.

Cathode Rays and electrons

Letter of the understanding that there were negative charged atoms; electrons

Charge to mass for electrons

JJ Thompson combined with other data to calculate charge and mass of electrons

Atomic nucleus

Thompson knew something else’s present because the electron mass is much lighter than the overall atomic mass.

so he created a model; the atom as a sphere of diffusely spread positively charged matter where tiny electrons were embedded.

What did Rutherford's gold foil experiment demonstrate?

There is a dense, positively charged nucleus in atoms, which contains protons surrounded by electrons.

Discovered protons

Neutron

Nuclear mass was higher than electron mass, so they propose that there’s a particle without a charge called neutrons.

Atomic theory today

Three cases made out of protons and neutrons and occupy a small central region of the atom.Neutrons have a mass, but are uncharged and contribute to the atomic mass.

electrons are outside of the nucleus.

Atom is neutral because the number of electrons equals the number of protons.

What is the charge and relative mass of a proton?

A proton has a charge of +1 and a mass of approximately 1 u.

What is the charge and relative mass of an electron ?

A proton has a charge of -1 and a mass of approximately 0 u.

What is the charge and relative mass of a neutron?

A neutron has a charge of 0 and a mass of approximately 1 u.

Does Emery atom of a given element have the same number of protons and/or neutrons?

Every atom has the same number of protons, but not the same number of neutrons.

How are isotopes defined?

Isotopes are atoms that have the same number of protons but different numbers of neutrons.

Must be nearly equal to its mass number

A/Z X

Z is the atomic number: number of protons in the nucleus of each atom of an element

A is the total number of protons and neutrons present in the nucleus of an atom of a particular isotope of an element

Solving for average atomic mass or percent abundance of isotopes

You multiply the isotopic mass with the percent abundance in decimal form and you add each isotope together

What is an average atomic mass?

Average atomic mass is the weighted average of the atomic masses of all isotopes of an element based on their natural abundance.

Groups in periodic table

Elements with similar properties are in the same group

period in periodic table.

Elements in a row of the periodic table going from the bottom to the top

Family or groups in periodic table

Group 1A: alkali metals

Group 2A: alkaline earth metals

Group 6A: oxygen group chalcogens

Group 7A: Halogens

Group 8A: Noble Gases

Metals

Good electrical and thermal conductivity they are ductile and malleable, and are lusterous in appearance.

Shine and can be hammered in into sheets

Nonmetals

Poor conductors, brittle and non-lusterous

Metalloids

Bright, silly, geeks, always, search, thoughtfully

Some metal like properties and some nonmetal characteristics

Periodic table organization

Systemization

What is the naming convention for binary acids?

For a monatomic anion, the acid name is formed by replacing the '-ide' ending with '-ic' and adding the prefix 'hydro-'.{

What does an ionic compound consist of?

An ionic compound consists of a metal that loses electrons (forming cations) and a nonmetal that gains those electrons (forming anions).

Opposites attract.

Nonmetal wants to achieve same number of electrons as atoms of nearest noble gas

Cation-cation repulsion and anion-anion repulsion

Naming ionic compound

Name of cation first and then name of anion

Roman numeral in parentheses to indicate the charge of the metal if they have more than one stable ionic state

Ionic compound formation

Electrostatic forces will fall off with distance

Crystalline structure, places, ions of opposite charge closer together than ions of like charge and attraction will dominate over repulsion

How to write ionic compounds?

You put a negative or a + on the top right of the element. The element cannot lose protons they can only lose or gain electrons. So if it has a positive charge, it means it lost that many electrons.

What indicates a covalent bond?

Covalent bonds arise when atoms (usually nonmetal w nonmetal) share electrons.

Forces present in equivalent bound

Repulsion between nuclei

Repulsion between electrons

Attraction between nuclei and electrons

Molecules

Ionic compounds are not molecules

Covalent compounds are molecules

Polyatomic ions are molecules

Formula unit

Ionic compound

Polyatomic ions

Group of atoms, Fowley bonded will gain or lose electrons and possess a non-zero charge

How is the molecular formula of a compound different from its empirical formula?

The molecular formula indicates the actual number of atoms of each element in a molecule, while the empirical formula shows the simplest whole-number ratio of elements.

What are structural formulas used for?

Structural formulas show the arrangement of atoms in a molecule and can depict the connectivity of atoms.

Ball and stick models

Shows the location locations of the centers of the atoms within a color-coded space filling figure that shows the distribution of charge around the atoms

Space filling model

Relative atomic sizes and distances between atoms

What are polyatomic ions?

Polyatomic ions are groups of covalently bonded atoms that carry a charge.

What are hydrates?

Hydrates are ionic compounds that contain a specific number of water molecules within their crystal structure.

Provide an example of a heterogeneous mixture.

Sand and water, oil and vinegar, or a salad are examples of heterogeneous mixtures.

Provide an example of a homogeneous mixture (solution).

Saltwater, sugar dissolved in water, or air are examples of homogeneous mixtures.

Where are electrons located within an atom?

Electrons are found in the electron cloud, rapidly moving around the nucleus.

In the notation (_Z^A X), what do A and Z represent?

A represents the mass number (total protons + neutrons), and Z represents the atomic number (number of protons).

What is the naming convention for binary ionic compounds composed of a metal and a nonmetal?

The metal's name is retained, followed by the nonmetal's root name with an '-ide' suffix. For example, NaCl is Sodium Chloride.