What is the density of water, and how does it determine if an object sinks or floats?

The density of water is 1 g/cm³. If an object's density is greater than 1 g/cm³, it will sink. If an object's density is less than 1 g/cm³, it will float.

How to calculate VOLUME if you have length, width, height?

Length x width x height. Ex: a block 3cmx3cmx3cm is 9cm³

How do you determine the DENSITY?

Density = Mass/Volume. Remember units: Mass is generally in grams (g); Volume is cm³ or mL; Density is g/cm³ or mL

Sub-particle of the atom. Location: INSIDE the nucleus. Charge: POSITIVE (+). Mass: contributes to most of the atom's mass (with neutrons). Balances atom's charge with electrons. IDENTITY of the atom → if protons change, the element changes. Number of protons = Atomic number (A = P = E).

The number of Protons determines the ----

IDENTITY of an element (what they are).

Sub-particle of atom. Location: INSIDE the nucleus. Charge: NEUTRAL (no charge). Mass: contributes to most of the atom's mass (with protons). To find number: Mass number - Atomic number.

Sub-particle of the atom. Location: OUTSIDE the nucleus, in electron cloud. Charge: NEGATIVE (-). Mass: very small, almost zero. Same number as protons (A = P = E). Balances the positive charge of protons.

Located in the center of the atom - Has MOST OF THE MASS because it contains both protons and neutrons.

Tells you: The number of protons (defines the element's identity). The number of electrons (in a neutral atom). Remember: A = P = E.

Protons + Neutrons. Always rounded to a whole number. Electrons do not count toward mass.

Located on the outermost energy level (last orbit). Found by looking at the last digit of the group #. Maximum: 8.

Atoms want 8 valence electrons in their outer shell. If they have 1 or 7, they are very reactive because they try to gain, lose, or share electrons to reach 8. Atoms are stable when their outer shell is full.

Vertical column in the periodic table. All the elements of the SAME GROUP have the same number of VALENCE ELECTRONS, REACT the SAME (they have SIMILAR CHEMICAL PROPERTIES).

Having Similar (Chemical) Properties means ----

"react the same". Elements with the same amount of VALENCE ELECTRONS (SAME GROUP/column/family) react the same. Mnemonic: People from the same group/family act the same way.

Chemical properties of an atom is determined by---

the number of VALENCE ELECTRONS.

Valence electrons determine the ---

Chemical properties (or Reactivity) of an element.

GROUP 1 - Very REACTIVE because they would do anything to lose that 1 valence electron in the last orbit to reach the "8 is great" underneath.

Atoms are stable when they have---

8 valence electrons (8 is great). They are not likely to bond (or react) because they do not need anything.

GROUPS on the periodic table are arranged

in COLUMNS. On top of the column, you can find the number of valence electrons from 1 in group 1 to 8 in group 18.

How do valence electrons differ from regular electrons?

They are in the outermost level and they determine the chemical properties of the element (how the element will react with others).

The most reactive elements are found...

in groups 1 and 17 of the periodic table because they want 8 valence electrons and are so close to it (need to lose one for Group 1 or gain one for Group 17).

The least reactive elements are found....

in group 18 (NOBLE GAS) because they have 8 valence electrons and don't need any more. Any element with 8 valence electrons will be the least reactive (it does not matter how many orbits, protons, neutrons, etc. LOOK AT THE NUMBER OF VALENCE ELECTRONS: 8 is GREAT!).

Gases that do not react (Noble gases).

Left to right ROWS (7 of them). It tells you the NUMBER OF ENERGY LEVELS. The elements of the SAME PERIOD have the SAME NUMBER of ENERGY LEVELS. Mnemonic: The sentences we write left to right end with periods.

Shiny, malleable, ductile, conductive (of electricity or heat). Ex: Gold, Silver.

Brittle, dull, poor conductors of heat and electricity, and have much lower melting and boiling points.

Electrons determine the----

REACTIVITY of an element (VALENCE ELECTRONS determine how the element bonds/reacts with other elements).

Which is less reactive between Aluminum (group 13) and Selenium (Group 16)?

Aluminum, with 3 valence electrons, because it is easier for Selenium (6 valence electrons) to try to gain 2 more electrons than for Aluminum to lose its 3.

HALOGENS are located in Group----

17 (next to Noble gases). They are very reactive because they are missing just one valence electron to reach the stable "octet" (perfect 8).

What are the elements to the RIGHT of the zigzag line called in the periodic table?

Nonmetals (includes halogens and noble gases).

How many valence electrons are in an atom with an atomic number of 6?

4. There are always 2 electrons in the first level and up to 8 in the next level, so we will have the 4 remaining electrons in the last orbit. 2+4=6.

How do you find the total number of protons and neutrons in an atom?

Look at the Atomic Mass (the long number with decimals) and round it up. ex: 15.999 is 16 but 39.098 is 39.

APE is a way to remember what?

Atomic number = Protons = Electrons (it is all the same number!).

MAN is a way to remember what?

Mass number - Atomic number = Neutrons.

What are other names for the Electron Cloud?

Orbitals, orbits, shells, energy levels.

How do you determine volume of a rock?

Measure water in a cylinder before placing the rock in water and after placing the rock. The difference in water level is the rock's volume.

How do you get the total number of subatomic particles?

Atomic mass (Protons and Neutrons) + Atomic number (Electrons).

What is the correct electron configuration? (How do they arrange themselves on the levels?)

2-8-8-8 Rule: The first energy level can hold a maximum of 2 electrons. The second and third levels can each hold up to 8 electrons. Electrons fill the levels in order, starting with the innermost. Example: Aluminum (Al) Aluminum has 13 electrons. First level: 2 electrons. Second level: 8 electrons. Third level: 3 electrons (the remaining ones). The electron configuration of Aluminum is 2-8-3.

What is the charge of an atom?

0 (No charge because they have the same number of positive protons and negative electrons).

Unit 2: PRACTICE Test - Density, Matter, Atoms, Periodic Table Flashcards

Student preview

59 questions

Show all answers

1.

FLASHCARD QUESTION

Front

What is a pure substance?

Back

Matter made of only one kind of particle. Cannot be separated by physical means. Includes Elements and some Compounds. Ex: Gold (Au), Iron (Fe), Water (H₂O)

2.

FLASHCARD QUESTION

Front

What is an element?

Back

Pure substance made of ONLY ONE TYPE of atom. Formula has 1 capital letter. Ex: O₂, C, Na

3.

FLASHCARD QUESTION

Front

What is a compound?

Back

Substance made of 2+ DIFFERENT elements that are CHEMICALLY COMBINED. Formula will have 2+ capital letters. Ex: H₂O, NaCl, CO₂

4.

FLASHCARD QUESTION

Front

What is a Molecule?

Back

2+ atoms bonded together (can be SAME OR DIFFERENT elements). Smallest unit of a compound to retain its properties. All compounds are molecules, but not all molecules are compounds. Ex: O₂ (molecule but NOT compound), H₂O (both molecule + compound)

5.

FLASHCARD QUESTION

Front

What is a Mixture?

Back

2+ substances PHYSICALLY COMBINED (NOT chemically). Can be separated physically. Ex: Salty water, Air, Trail Mix

6.

FLASHCARD QUESTION

Front

What is a Homogeneous mixture?

Back

Looks the SAME throughout (uniform). Ex: Salt dissolved in water, Air, Lemonade, Kool-Aid

7.

FLASHCARD QUESTION

Front

What is a Heterogeneous mixture?

Back

Visibly DIFFERENT parts (not uniform). Ex: Salad, Trail mix, Oil & water

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