science test :(

What makes an atom stable?

By having a full set of valence electrons.

Covalent Bond

Atoms bond by sharing valence electrons and completing each other.

Ion

A charge based on an imbalance of protons to electrons.

Ionic Bond

A bond formed by the attraction of opposite charged ions.

When is an atom not an ion?

When they are not charged.

Halogens

Atoms that need one more valence electron and take one from another atom, gaining one and making the atom lose theirs.

Alkali Metals

Elements that are not stable and only have one electron.

Alkali Earth Metals

Elements with 2 valence electrons, more stable than alkali metals but still unstable.

Transition Metals

Metals, semimetals, and non-metals that serve as a bridge between the two sides of the periodic table.

Halogen

An atom that has 7 valence electrons and has a property called electronegativity.

Noble Gases

Stable elements that have a full set of valence electrons.

Atom

A single unit of matter that cannot be broken down further.

Element

A collection of the same atoms together (unbonded).

Molecule

Two or more atoms bonded together.

Homonuclear Diatomic Molecule

What it is called when 2 of the same atoms bond together.

Compound

What it is called when 2 or more different atoms bond together.

Chemical Reaction

When molecular bonds break and atoms rearrange differently, making new substances.

Signs of a chemical reaction

Instant bubbles, temperature change, precipitation formation, color change, and odor.

Physical Reaction

A change in appearance, but molecules remain the same.

Law of Conservation of Mass/Matter

In every chemical reaction, no atoms are lost or gained; matter is neither created nor destroyed.

Stoichiometry

The process of balancing chemical equations.

What is between the bonds between molecules?

Energy.

pH level for acids

0-6.99.

pH level for bases (alkali)

7.1-14.

What is the natural pH level?

Indicator for pH

Red cabbage.

Taste of acids

Sour.

Taste of bases

Bitter.

Endothermic Process

An energy process where energy is absorbed from the environment.

Exothermic Process

An energy process where energy is released into the environment.

Is melting ice endothermic or exothermic?

Endothermic.

Is photosynthesis endothermic or exothermic?

Endothermic.

Is water evaporation into gas endothermic or exothermic?

Endothermic.

Are fireworks endothermic or exothermic?

Exothermic.

Is water turning into ice endothermic or exothermic?

Exothermic.

Are hand warmers endothermic or exothermic?

Exothermic.

Synthetic

Something that is not natural but starts from natural materials.

Natural

Something that comes from nature.

Is artificial sweetener synthetic or natural?

Synthetic.

Are vegetarian burgers synthetic or natural?

Natural if all plant-based; synthetic if it contains non-natural meat substances.

Are McDonald's burgers synthetic or natural?

Synthetic.